あ ループ を実行できるようにするプログラミング制御構造です。 コードのブロック 特定の条件を満たせば無期限。ループは、繰り返しアクティビティを実行し、プログラミングのパフォーマンスを向上させるために使用されます。 C プログラミング言語には複数のループがあり、その 1 つが 「do-while」ループ 。
あ 「do-while」ループ の形式です ループ C では、最初にコード ブロックを実行し、その後に条件を実行します。条件が 真実 、 ループ 走り続けます。それ以外の場合は停止します。ただし、その状態が元々あるかどうかは、 真実 、コード ブロックが少なくとも 1 回実行されることが保証されます。
do while ループ構文
C 言語の do-while ループの構文は次のとおりです。
do{ //code to be executed }while(condition); コンポーネントは次のように分かれています。
catchブロックJavaを試してください
- の キーワードを実行します ループの始まりを示します。
- の コードブロック 内で 中括弧 {} ループの本体であり、繰り返したいコードが含まれます。
- の while キーワード 括弧 () で囲まれた条件が続きます。コード ブロックが実行された後、この条件が検証されます。条件が 真実 、ループは継続します。それ以外の場合、 ループの終了 。
C での do while ループの動作
例を見てみましょう。 do-while ループ この例では、ユーザーに質問する簡単なプログラムを作成します。 パスワード 正しいパスワードが入力されるまで尋ね続けます。
例：
#include #include int main() { char password[] = 'secret'; char input[20]; do { printf('Enter the password: '); scanf('%s', input); } while (strcmp(input, password) != 0); printf('Access granted!
'); return 0; } プログラムは次のように実行されます。
- 次のヘッダー ファイルが含まれています。 標準用 入力 そして 出力 ルーチンと 文字列用 操作関数 。
- 正しいパスワードは次のように定義されます。 文字配列 (char パスワード[]) 値と一緒に '秘密'
- その後、ユーザーの入力を保存する別の文字配列 input を定義します。
- の キーワードを実行します 内に含まれるコード ブロックを示します。 ループ 少なくとも 1 回は実行されます。
- の使用 printf()関数 、ループ内でユーザーにパスワードの入力を求めるプロンプトを表示します。
- 次に、 ユーザーの入力 を使用して scanf()関数 そしてそれを 入力配列 。
- を読んだ後、 入力 を使用します。 strcmp() 関数 入力を正しいパスワードと比較します。文字列が 等しい、 の strcmp関数 0 を返します。そのため、入力とパスワードが等しくない限りループを続けます。
- 一度 正しいパスワード が入力されるとループが終了し、出力します。 「アクセスが許可されました!」 を使用して printf()関数 。
- その後、プログラムは実行が成功したことを示す 0 を返します。
出力：
考えられるシナリオを見てみましょう。
Enter the password: 123 Enter the password: abc Enter the password: secret Access Granted!
説明：
この例では、ユーザーは最初に間違ったパスワードを入力します。 「123」 そして 「ABC」 。ループは、正しいパスワードが入力されるまでユーザーにプロンプトを表示します。 '秘密' が入力されています。正しいパスワードが入力されると、ループは終了し、 「アクセスが許可されました!」 というメッセージが表示されます。
C での do while ループの例:
例 1:
以下に簡単な例を示します。 「do-while」ループ 1 から 5 までの数字を出力する C の場合:
#include int main() { inti = 1; do { printf('%d
', i); i++; } while (i<= 5); return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> 1 2 3 4 5 </pre> <p> <strong>Explanation:</strong> </p> <p>In this example, the <strong> <em>code block</em> </strong> within the do loop will be executed at least once, printing numbers from <strong> <em>1 to 5</em> </strong> . After each iteration, the <strong> <em>i value</em> </strong> is incremented, and the condition <strong> <em>i<= 5< em> </=></em></strong> is checked. If the condition is still true, the loop continues; otherwise, it terminates.</p> <p> <strong>Example 2:</strong> </p> <p>Program to print table for the given number using do while Loop</p> <pre> #include intmain(){ inti=1,number=0; printf('Enter a number: '); scanf('%d',&number); do{ printf('%d
',(number*i)); i++; }while(i<=10); return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> Enter a number: 5 5 10 15 20 25 30 35 40 45 50 Enter a number: 10 10 20 30 40 50 60 70 80 90 100 </pre> <p> <strong>Example 3:</strong> </p> <p>Let's take a program that prints the multiplication table of a given number N using a <strong> <em>do...while Loop</em> :</strong> </p> <pre> #include int main() { int N; printf('Enter a number to generate its multiplication table: '); scanf('%d', &N); inti = 1; do { printf('%d x %d = %d
', N, i, N * i); i++; } while (i<= 10); return 0; } < pre> <p> <strong>Output:</strong> </p> <p>Let us say you enter the number 7 as input:</p> <pre> Please enter a number to generate its multiplication table: 7 7 x 1 = 7 7 x 2 = 14 7 x 3 = 21 7 x 4 = 28 7 x 5 = 35 7 x 6 = 42 7 x 7 = 49 7 x 8 = 56 7 x 9 = 63 7 x 10 = 70 </pre> <p>The program calculates and prints the multiplication table for <strong> <em>7</em> </strong> from 1 to 10.</p> <h3>Infinite do while loop</h3> <p>An <strong> <em>infinite loop</em> </strong> is a loop that runs indefinitely as its condition is always <strong> <em>true</em> </strong> or it lacks a terminating condition. Here is an example of an <strong> <em>infinite do...while loop</em> </strong> in C:</p> <p> <strong>Example:</strong> </p> <pre> #include int main() { inti = 1; do { printf('Iteration %d
', i); i++; } while (1); // Condition is always true return 0; } </pre> <p>In this <strong> <em>example</em> </strong> , the <strong> <em>loop</em> </strong> will keep running <strong> <em>indefinitely</em> </strong> because <strong> <em>condition 1</em> </strong> is always <strong> <em>true</em> </strong> .</p> <p> <strong>Output:</strong> </p> <p>When you run the program, you will see that it continues printing <strong> <em>'Iteration x',</em> </strong> where x is the <strong> <em>iteration number</em> </strong> without stopping:</p> <pre> Iteration 1 Iteration 2 Iteration 3 Iteration 4 Iteration 5 ... (and so on) </pre> <p>To interrupt an infinite loop like this, you generally use a <strong> <em>break statement</em> </strong> within the <strong> <em>loop</em> </strong> or some external condition you can control, such as <strong> <em>hitting</em> </strong> a specific key combination. In most desktop settings, the keyboard shortcut <strong> <em>Ctrl+C</em> </strong> can escape the Loop.</p> <h3>Nested do while loop in C</h3> <p>In C, we take an example of a <strong> <em>nested do...while loop</em> </strong> . In this example, we will write a program that uses <strong> <em>nested do...while loops</em> </strong> to create a numerical pattern.</p> <p> <strong>Example:</strong> </p> <pre> #include int main() { int rows, i = 1; printf('Enter the number of rows: '); scanf('%d', &rows); do { int j = 1; do { printf('%d ', j); j++; } while (j <= i); printf('
'); i++; } while (i<="rows);" return 0; < pre> <p>In this program, we use <strong> <em>nested do...while loops</em> </strong> to generate a pattern of numbers. The <strong> <em>outer loop</em> </strong> controls the number of rows, and the <strong> <em>inner loop</em> </strong> generates the numbers for each row.</p> <p> <strong>Output:</strong> </p> <p>Let us say you input five as the number of rows:</p> <pre> Enter the number of rows: 5 1 1 2 1 2 3 1 2 3 4 1 2 3 4 5 </pre> <p> <strong>Explanation:</strong> </p> <p>In this example, the program generates a pattern of numbers in a <strong> <em>triangular shape</em> </strong> . The <strong> <em>outer loop</em> </strong> iterates over the rows, and the <strong> <em>inner loop</em> </strong> iterates within each row, printing the numbers from 1 up to the current row number.</p> <h2>Difference between while and do while Loop</h2> <p>Here is a tabular comparison between the while loop and the do-while Loop in C:</p> <table class="table"> <tr> <th>Aspect</th> <th>while loop</th> <th>do-while loop</th> </tr> <tr> <td> <strong>Syntax</strong> </td> <td>while (condition) { ... }</td> <td>do { ... } while (condition);</td> </tr> <tr> <td> <strong>Loop Body Execution</strong> </td> <td>Condition is checked before execution.</td> <td>The body is executed before the condition.</td> </tr> <tr> <td> <strong>First Execution</strong> </td> <td>The condition must be true initially.</td> <td>The body is executed at least once.</td> </tr> <tr> <td> <strong>Loop Execution</strong> </td> <td>May execute zero or more times.</td> <td>Will execute at least once.</td> </tr> <tr> <td> <strong>Example</strong> </td> <td>while (i<5) { printf('%d
', i); i++; }< td> <td>do { printf('%d
', i); i++; } while (i<5);< td> </5);<></td></5)></td></tr> <tr> <td> <strong>Common Use Cases</strong> </td> <td>When the loop may not run at all.</td> <td>When you want the loop to run at least once.</td> </tr> </table> <p> <strong>While Loop:</strong> The loop body is executed before the condition is checked. If the condition is initially <strong> <em>false</em> </strong> , the loop may not execute.</p> <p> <strong>Do-while Loop:</strong> The <strong> <em>loop body</em> </strong> is executed at least once before the condition is <strong> <em>checked</em> </strong> . This guarantees that the loop completes at least one iteration.</p> <p>When you want the <strong> <em>loop</em> </strong> to run based on a condition that may be <strong> <em>false</em> </strong> at first, use the <strong> <em>while loop</em> </strong> , and when you want the loop to run at least once regardless of the starting state, use the <strong> <em>do-while loop.</em> </strong> </p> <h2>Features of do while loop</h2> <p>The do-while loop in C has several fundamental characteristics that make it an effective programming technique in certain situations. The following are the significant characteristics of the do-while loop:</p> <ul> <tr><td>Guaranteed Execution:</td> Unlike other <strong> <em>loop structures</em> </strong> , the <strong> <em>do-while oop</em> </strong> ensures that the loop body is executed at least once. Because the condition is assessed after the loop body, the code within the loop is performed before the condition is verified. </tr><tr><td>Loop after testing:</td> The <strong> <em>do-while loop</em> </strong> is a post-tested loop which implies that the loop condition is assessed after the loop body has been executed. If the condition is true, the loop body is run once again. This behavior allows you to verify the condition for repetition before ensuring that a given activity is completed. </tr><tr><td>Conditionally Controlled:</td> The loop continues to execute as long as the condition specified after the while keyword remains <strong> <em>true</em> </strong> . When the condition evaluates to <strong> <em>false</em> </strong> , the loop is terminated, and control shifts to the sentence after the loop. </tr><tr><td>Flexibility:</td> The <strong> <em>do-while loop</em> </strong> may be utilized in several contexts. It is typically used in cases where a piece of code must be executed at least once, such as <strong> <em>menu-driven programs, input validation,</em> </strong> or <strong> <em>repetitive computations</em> </strong> . </tr><tr><td>Nesting Capability:</td> Similar to other <strong> <em>loop constructs</em> </strong> , the <strong> <em>do-while loop</em> </strong> can be <strong> <em>nested</em> </strong> inside other <strong> <em>loops</em> </strong> or <strong> <em>control structures</em> </strong> to create more complex control flow patterns. It allows for the creation of <strong> <em>nested loops</em> </strong> and the implementation of intricate repetitive tasks. </tr><tr><td>Break and Continue:</td> The break statement can be used within a <strong> <em>do-while loop</em> </strong> to terminate the loop execution and exit the loop prematurely. The <strong> <em>continue statement</em> </strong> can skip the remaining code in the current iteration and jump to the next iteration of the loop. </tr><tr><td>Local Scope:</td> Variables declared inside the <strong> <em>do-while loop</em> </strong> body have local scope and are accessible only within the <strong> <em>loop block.</em> </strong> They cannot be accessed outside the loop or by other loops or control structures. </tr><tr><td>Infinite Loop Control:</td> It is crucial to ensure that the loop's condition is eventually modified within the <strong> <em>loop body</em> </strong> . This modification is necessary to prevent infinite loops where the condition continually evaluates to true. Modifying the condition ensures that the loop terminates at some point. </tr></ul> <hr></=></pre></=></pre></=10);></pre></=> 説明：
この例では、 コードブロック do ループ内で少なくとも 1 回実行され、からの数値を出力します。 1～5 。各反復の後、 私は〜を重視します が増加し、条件が 私<= 5< em> にチェックが入っています。条件が依然として true の場合、ループは継続します。それ以外の場合は終了します。
例 2:
do whileループを使用して指定された番号のテーブルを出力するプログラム
#include intmain(){ inti=1,number=0; printf('Enter a number: '); scanf('%d',&number); do{ printf('%d
',(number*i)); i++; }while(i<=10); return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> Enter a number: 5 5 10 15 20 25 30 35 40 45 50 Enter a number: 10 10 20 30 40 50 60 70 80 90 100 </pre> <p> <strong>Example 3:</strong> </p> <p>Let's take a program that prints the multiplication table of a given number N using a <strong> <em>do...while Loop</em> :</strong> </p> <pre> #include int main() { int N; printf('Enter a number to generate its multiplication table: '); scanf('%d', &N); inti = 1; do { printf('%d x %d = %d
', N, i, N * i); i++; } while (i<= 10); return 0; } < pre> <p> <strong>Output:</strong> </p> <p>Let us say you enter the number 7 as input:</p> <pre> Please enter a number to generate its multiplication table: 7 7 x 1 = 7 7 x 2 = 14 7 x 3 = 21 7 x 4 = 28 7 x 5 = 35 7 x 6 = 42 7 x 7 = 49 7 x 8 = 56 7 x 9 = 63 7 x 10 = 70 </pre> <p>The program calculates and prints the multiplication table for <strong> <em>7</em> </strong> from 1 to 10.</p> <h3>Infinite do while loop</h3> <p>An <strong> <em>infinite loop</em> </strong> is a loop that runs indefinitely as its condition is always <strong> <em>true</em> </strong> or it lacks a terminating condition. Here is an example of an <strong> <em>infinite do...while loop</em> </strong> in C:</p> <p> <strong>Example:</strong> </p> <pre> #include int main() { inti = 1; do { printf('Iteration %d
', i); i++; } while (1); // Condition is always true return 0; } </pre> <p>In this <strong> <em>example</em> </strong> , the <strong> <em>loop</em> </strong> will keep running <strong> <em>indefinitely</em> </strong> because <strong> <em>condition 1</em> </strong> is always <strong> <em>true</em> </strong> .</p> <p> <strong>Output:</strong> </p> <p>When you run the program, you will see that it continues printing <strong> <em>'Iteration x',</em> </strong> where x is the <strong> <em>iteration number</em> </strong> without stopping:</p> <pre> Iteration 1 Iteration 2 Iteration 3 Iteration 4 Iteration 5 ... (and so on) </pre> <p>To interrupt an infinite loop like this, you generally use a <strong> <em>break statement</em> </strong> within the <strong> <em>loop</em> </strong> or some external condition you can control, such as <strong> <em>hitting</em> </strong> a specific key combination. In most desktop settings, the keyboard shortcut <strong> <em>Ctrl+C</em> </strong> can escape the Loop.</p> <h3>Nested do while loop in C</h3> <p>In C, we take an example of a <strong> <em>nested do...while loop</em> </strong> . In this example, we will write a program that uses <strong> <em>nested do...while loops</em> </strong> to create a numerical pattern.</p> <p> <strong>Example:</strong> </p> <pre> #include int main() { int rows, i = 1; printf('Enter the number of rows: '); scanf('%d', &rows); do { int j = 1; do { printf('%d ', j); j++; } while (j <= i); printf(\'
\'); i++; } while (i<="rows);" return 0; < pre> <p>In this program, we use <strong> <em>nested do...while loops</em> </strong> to generate a pattern of numbers. The <strong> <em>outer loop</em> </strong> controls the number of rows, and the <strong> <em>inner loop</em> </strong> generates the numbers for each row.</p> <p> <strong>Output:</strong> </p> <p>Let us say you input five as the number of rows:</p> <pre> Enter the number of rows: 5 1 1 2 1 2 3 1 2 3 4 1 2 3 4 5 </pre> <p> <strong>Explanation:</strong> </p> <p>In this example, the program generates a pattern of numbers in a <strong> <em>triangular shape</em> </strong> . The <strong> <em>outer loop</em> </strong> iterates over the rows, and the <strong> <em>inner loop</em> </strong> iterates within each row, printing the numbers from 1 up to the current row number.</p> <h2>Difference between while and do while Loop</h2> <p>Here is a tabular comparison between the while loop and the do-while Loop in C:</p> <table class="table"> <tr> <th>Aspect</th> <th>while loop</th> <th>do-while loop</th> </tr> <tr> <td> <strong>Syntax</strong> </td> <td>while (condition) { ... }</td> <td>do { ... } while (condition);</td> </tr> <tr> <td> <strong>Loop Body Execution</strong> </td> <td>Condition is checked before execution.</td> <td>The body is executed before the condition.</td> </tr> <tr> <td> <strong>First Execution</strong> </td> <td>The condition must be true initially.</td> <td>The body is executed at least once.</td> </tr> <tr> <td> <strong>Loop Execution</strong> </td> <td>May execute zero or more times.</td> <td>Will execute at least once.</td> </tr> <tr> <td> <strong>Example</strong> </td> <td>while (i<5) { printf(\'%d
\', i); i++; }< td> <td>do { printf('%d
', i); i++; } while (i<5);< td> </5);<></td></5)></td></tr> <tr> <td> <strong>Common Use Cases</strong> </td> <td>When the loop may not run at all.</td> <td>When you want the loop to run at least once.</td> </tr> </table> <p> <strong>While Loop:</strong> The loop body is executed before the condition is checked. If the condition is initially <strong> <em>false</em> </strong> , the loop may not execute.</p> <p> <strong>Do-while Loop:</strong> The <strong> <em>loop body</em> </strong> is executed at least once before the condition is <strong> <em>checked</em> </strong> . This guarantees that the loop completes at least one iteration.</p> <p>When you want the <strong> <em>loop</em> </strong> to run based on a condition that may be <strong> <em>false</em> </strong> at first, use the <strong> <em>while loop</em> </strong> , and when you want the loop to run at least once regardless of the starting state, use the <strong> <em>do-while loop.</em> </strong> </p> <h2>Features of do while loop</h2> <p>The do-while loop in C has several fundamental characteristics that make it an effective programming technique in certain situations. The following are the significant characteristics of the do-while loop:</p> <ul> <tr><td>Guaranteed Execution:</td> Unlike other <strong> <em>loop structures</em> </strong> , the <strong> <em>do-while oop</em> </strong> ensures that the loop body is executed at least once. Because the condition is assessed after the loop body, the code within the loop is performed before the condition is verified. </tr><tr><td>Loop after testing:</td> The <strong> <em>do-while loop</em> </strong> is a post-tested loop which implies that the loop condition is assessed after the loop body has been executed. If the condition is true, the loop body is run once again. This behavior allows you to verify the condition for repetition before ensuring that a given activity is completed. </tr><tr><td>Conditionally Controlled:</td> The loop continues to execute as long as the condition specified after the while keyword remains <strong> <em>true</em> </strong> . When the condition evaluates to <strong> <em>false</em> </strong> , the loop is terminated, and control shifts to the sentence after the loop. </tr><tr><td>Flexibility:</td> The <strong> <em>do-while loop</em> </strong> may be utilized in several contexts. It is typically used in cases where a piece of code must be executed at least once, such as <strong> <em>menu-driven programs, input validation,</em> </strong> or <strong> <em>repetitive computations</em> </strong> . </tr><tr><td>Nesting Capability:</td> Similar to other <strong> <em>loop constructs</em> </strong> , the <strong> <em>do-while loop</em> </strong> can be <strong> <em>nested</em> </strong> inside other <strong> <em>loops</em> </strong> or <strong> <em>control structures</em> </strong> to create more complex control flow patterns. It allows for the creation of <strong> <em>nested loops</em> </strong> and the implementation of intricate repetitive tasks. </tr><tr><td>Break and Continue:</td> The break statement can be used within a <strong> <em>do-while loop</em> </strong> to terminate the loop execution and exit the loop prematurely. The <strong> <em>continue statement</em> </strong> can skip the remaining code in the current iteration and jump to the next iteration of the loop. </tr><tr><td>Local Scope:</td> Variables declared inside the <strong> <em>do-while loop</em> </strong> body have local scope and are accessible only within the <strong> <em>loop block.</em> </strong> They cannot be accessed outside the loop or by other loops or control structures. </tr><tr><td>Infinite Loop Control:</td> It is crucial to ensure that the loop's condition is eventually modified within the <strong> <em>loop body</em> </strong> . This modification is necessary to prevent infinite loops where the condition continually evaluates to true. Modifying the condition ensures that the loop terminates at some point. </tr></ul> <hr></=></pre></=></pre></=10);> 例 3:
を使用して、指定された数値 N の九九を出力するプログラムを考えてみましょう。 do...while ループ :
#include int main() { int N; printf('Enter a number to generate its multiplication table: '); scanf('%d', &N); inti = 1; do { printf('%d x %d = %d
', N, i, N * i); i++; } while (i<= 10); return 0; } < pre> <p> <strong>Output:</strong> </p> <p>Let us say you enter the number 7 as input:</p> <pre> Please enter a number to generate its multiplication table: 7 7 x 1 = 7 7 x 2 = 14 7 x 3 = 21 7 x 4 = 28 7 x 5 = 35 7 x 6 = 42 7 x 7 = 49 7 x 8 = 56 7 x 9 = 63 7 x 10 = 70 </pre> <p>The program calculates and prints the multiplication table for <strong> <em>7</em> </strong> from 1 to 10.</p> <h3>Infinite do while loop</h3> <p>An <strong> <em>infinite loop</em> </strong> is a loop that runs indefinitely as its condition is always <strong> <em>true</em> </strong> or it lacks a terminating condition. Here is an example of an <strong> <em>infinite do...while loop</em> </strong> in C:</p> <p> <strong>Example:</strong> </p> <pre> #include int main() { inti = 1; do { printf('Iteration %d
', i); i++; } while (1); // Condition is always true return 0; } </pre> <p>In this <strong> <em>example</em> </strong> , the <strong> <em>loop</em> </strong> will keep running <strong> <em>indefinitely</em> </strong> because <strong> <em>condition 1</em> </strong> is always <strong> <em>true</em> </strong> .</p> <p> <strong>Output:</strong> </p> <p>When you run the program, you will see that it continues printing <strong> <em>'Iteration x',</em> </strong> where x is the <strong> <em>iteration number</em> </strong> without stopping:</p> <pre> Iteration 1 Iteration 2 Iteration 3 Iteration 4 Iteration 5 ... (and so on) </pre> <p>To interrupt an infinite loop like this, you generally use a <strong> <em>break statement</em> </strong> within the <strong> <em>loop</em> </strong> or some external condition you can control, such as <strong> <em>hitting</em> </strong> a specific key combination. In most desktop settings, the keyboard shortcut <strong> <em>Ctrl+C</em> </strong> can escape the Loop.</p> <h3>Nested do while loop in C</h3> <p>In C, we take an example of a <strong> <em>nested do...while loop</em> </strong> . In this example, we will write a program that uses <strong> <em>nested do...while loops</em> </strong> to create a numerical pattern.</p> <p> <strong>Example:</strong> </p> <pre> #include int main() { int rows, i = 1; printf('Enter the number of rows: '); scanf('%d', &rows); do { int j = 1; do { printf('%d ', j); j++; } while (j <= i); printf(\'
\'); i++; } while (i<="rows);" return 0; < pre> <p>In this program, we use <strong> <em>nested do...while loops</em> </strong> to generate a pattern of numbers. The <strong> <em>outer loop</em> </strong> controls the number of rows, and the <strong> <em>inner loop</em> </strong> generates the numbers for each row.</p> <p> <strong>Output:</strong> </p> <p>Let us say you input five as the number of rows:</p> <pre> Enter the number of rows: 5 1 1 2 1 2 3 1 2 3 4 1 2 3 4 5 </pre> <p> <strong>Explanation:</strong> </p> <p>In this example, the program generates a pattern of numbers in a <strong> <em>triangular shape</em> </strong> . The <strong> <em>outer loop</em> </strong> iterates over the rows, and the <strong> <em>inner loop</em> </strong> iterates within each row, printing the numbers from 1 up to the current row number.</p> <h2>Difference between while and do while Loop</h2> <p>Here is a tabular comparison between the while loop and the do-while Loop in C:</p> <table class="table"> <tr> <th>Aspect</th> <th>while loop</th> <th>do-while loop</th> </tr> <tr> <td> <strong>Syntax</strong> </td> <td>while (condition) { ... }</td> <td>do { ... } while (condition);</td> </tr> <tr> <td> <strong>Loop Body Execution</strong> </td> <td>Condition is checked before execution.</td> <td>The body is executed before the condition.</td> </tr> <tr> <td> <strong>First Execution</strong> </td> <td>The condition must be true initially.</td> <td>The body is executed at least once.</td> </tr> <tr> <td> <strong>Loop Execution</strong> </td> <td>May execute zero or more times.</td> <td>Will execute at least once.</td> </tr> <tr> <td> <strong>Example</strong> </td> <td>while (i<5) { printf(\'%d
\', i); i++; }< td> <td>do { printf('%d
', i); i++; } while (i<5);< td> </5);<></td></5)></td></tr> <tr> <td> <strong>Common Use Cases</strong> </td> <td>When the loop may not run at all.</td> <td>When you want the loop to run at least once.</td> </tr> </table> <p> <strong>While Loop:</strong> The loop body is executed before the condition is checked. If the condition is initially <strong> <em>false</em> </strong> , the loop may not execute.</p> <p> <strong>Do-while Loop:</strong> The <strong> <em>loop body</em> </strong> is executed at least once before the condition is <strong> <em>checked</em> </strong> . This guarantees that the loop completes at least one iteration.</p> <p>When you want the <strong> <em>loop</em> </strong> to run based on a condition that may be <strong> <em>false</em> </strong> at first, use the <strong> <em>while loop</em> </strong> , and when you want the loop to run at least once regardless of the starting state, use the <strong> <em>do-while loop.</em> </strong> </p> <h2>Features of do while loop</h2> <p>The do-while loop in C has several fundamental characteristics that make it an effective programming technique in certain situations. The following are the significant characteristics of the do-while loop:</p> <ul> <tr><td>Guaranteed Execution:</td> Unlike other <strong> <em>loop structures</em> </strong> , the <strong> <em>do-while oop</em> </strong> ensures that the loop body is executed at least once. Because the condition is assessed after the loop body, the code within the loop is performed before the condition is verified. </tr><tr><td>Loop after testing:</td> The <strong> <em>do-while loop</em> </strong> is a post-tested loop which implies that the loop condition is assessed after the loop body has been executed. If the condition is true, the loop body is run once again. This behavior allows you to verify the condition for repetition before ensuring that a given activity is completed. </tr><tr><td>Conditionally Controlled:</td> The loop continues to execute as long as the condition specified after the while keyword remains <strong> <em>true</em> </strong> . When the condition evaluates to <strong> <em>false</em> </strong> , the loop is terminated, and control shifts to the sentence after the loop. </tr><tr><td>Flexibility:</td> The <strong> <em>do-while loop</em> </strong> may be utilized in several contexts. It is typically used in cases where a piece of code must be executed at least once, such as <strong> <em>menu-driven programs, input validation,</em> </strong> or <strong> <em>repetitive computations</em> </strong> . </tr><tr><td>Nesting Capability:</td> Similar to other <strong> <em>loop constructs</em> </strong> , the <strong> <em>do-while loop</em> </strong> can be <strong> <em>nested</em> </strong> inside other <strong> <em>loops</em> </strong> or <strong> <em>control structures</em> </strong> to create more complex control flow patterns. It allows for the creation of <strong> <em>nested loops</em> </strong> and the implementation of intricate repetitive tasks. </tr><tr><td>Break and Continue:</td> The break statement can be used within a <strong> <em>do-while loop</em> </strong> to terminate the loop execution and exit the loop prematurely. The <strong> <em>continue statement</em> </strong> can skip the remaining code in the current iteration and jump to the next iteration of the loop. </tr><tr><td>Local Scope:</td> Variables declared inside the <strong> <em>do-while loop</em> </strong> body have local scope and are accessible only within the <strong> <em>loop block.</em> </strong> They cannot be accessed outside the loop or by other loops or control structures. </tr><tr><td>Infinite Loop Control:</td> It is crucial to ensure that the loop's condition is eventually modified within the <strong> <em>loop body</em> </strong> . This modification is necessary to prevent infinite loops where the condition continually evaluates to true. Modifying the condition ensures that the loop terminates at some point. </tr></ul> <hr></=></pre></=> プログラムは次の九九を計算して出力します。 7 1から10まで。
無限の do while ループ
アン 無限ループ 条件が常に次であるため、無限に実行されるループです。 真実 または終了条件がありません。以下はその一例です 無限 do...while ループ Cで:
例：
#include int main() { inti = 1; do { printf('Iteration %d
', i); i++; } while (1); // Condition is always true return 0; } この中で 例 、 ループ 走り続けます 無限に なぜなら 条件1 いつも 真実 。
出力：
プログラムを実行すると、印刷が継続されることがわかります。 '反復 x'、 ここで、x は 反復数 止まらずに：
Iteration 1 Iteration 2 Iteration 3 Iteration 4 Iteration 5 ... (and so on)
このような無限ループを中断するには、通常、 ブレークステートメント 以内 ループ または、制御できる外部条件など ヒッティング 特定のキーの組み合わせ。ほとんどのデスクトップ設定では、キーボード ショートカット Ctrl+C ループから抜け出すことができます。
C の入れ子になった do while ループ
C では、次の例を取り上げます。 ネストされた do...while ループ 。この例では、次を使用するプログラムを作成します。 ネストされた do...while ループ 数値パターンを作成します。
例：
#include int main() { int rows, i = 1; printf('Enter the number of rows: '); scanf('%d', &rows); do { int j = 1; do { printf('%d ', j); j++; } while (j <= i); printf(\'
\'); i++; } while (i<="rows);" return 0; < pre> <p>In this program, we use <strong> <em>nested do...while loops</em> </strong> to generate a pattern of numbers. The <strong> <em>outer loop</em> </strong> controls the number of rows, and the <strong> <em>inner loop</em> </strong> generates the numbers for each row.</p> <p> <strong>Output:</strong> </p> <p>Let us say you input five as the number of rows:</p> <pre> Enter the number of rows: 5 1 1 2 1 2 3 1 2 3 4 1 2 3 4 5 </pre> <p> <strong>Explanation:</strong> </p> <p>In this example, the program generates a pattern of numbers in a <strong> <em>triangular shape</em> </strong> . The <strong> <em>outer loop</em> </strong> iterates over the rows, and the <strong> <em>inner loop</em> </strong> iterates within each row, printing the numbers from 1 up to the current row number.</p> <h2>Difference between while and do while Loop</h2> <p>Here is a tabular comparison between the while loop and the do-while Loop in C:</p> <table class="table"> <tr> <th>Aspect</th> <th>while loop</th> <th>do-while loop</th> </tr> <tr> <td> <strong>Syntax</strong> </td> <td>while (condition) { ... }</td> <td>do { ... } while (condition);</td> </tr> <tr> <td> <strong>Loop Body Execution</strong> </td> <td>Condition is checked before execution.</td> <td>The body is executed before the condition.</td> </tr> <tr> <td> <strong>First Execution</strong> </td> <td>The condition must be true initially.</td> <td>The body is executed at least once.</td> </tr> <tr> <td> <strong>Loop Execution</strong> </td> <td>May execute zero or more times.</td> <td>Will execute at least once.</td> </tr> <tr> <td> <strong>Example</strong> </td> <td>while (i<5) { printf(\'%d
\', i); i++; }< td> <td>do { printf('%d
', i); i++; } while (i<5);< td> </5);<></td></5)></td></tr> <tr> <td> <strong>Common Use Cases</strong> </td> <td>When the loop may not run at all.</td> <td>When you want the loop to run at least once.</td> </tr> </table> <p> <strong>While Loop:</strong> The loop body is executed before the condition is checked. If the condition is initially <strong> <em>false</em> </strong> , the loop may not execute.</p> <p> <strong>Do-while Loop:</strong> The <strong> <em>loop body</em> </strong> is executed at least once before the condition is <strong> <em>checked</em> </strong> . This guarantees that the loop completes at least one iteration.</p> <p>When you want the <strong> <em>loop</em> </strong> to run based on a condition that may be <strong> <em>false</em> </strong> at first, use the <strong> <em>while loop</em> </strong> , and when you want the loop to run at least once regardless of the starting state, use the <strong> <em>do-while loop.</em> </strong> </p> <h2>Features of do while loop</h2> <p>The do-while loop in C has several fundamental characteristics that make it an effective programming technique in certain situations. The following are the significant characteristics of the do-while loop:</p> <ul> <tr><td>Guaranteed Execution:</td> Unlike other <strong> <em>loop structures</em> </strong> , the <strong> <em>do-while oop</em> </strong> ensures that the loop body is executed at least once. Because the condition is assessed after the loop body, the code within the loop is performed before the condition is verified. </tr><tr><td>Loop after testing:</td> The <strong> <em>do-while loop</em> </strong> is a post-tested loop which implies that the loop condition is assessed after the loop body has been executed. If the condition is true, the loop body is run once again. This behavior allows you to verify the condition for repetition before ensuring that a given activity is completed. </tr><tr><td>Conditionally Controlled:</td> The loop continues to execute as long as the condition specified after the while keyword remains <strong> <em>true</em> </strong> . When the condition evaluates to <strong> <em>false</em> </strong> , the loop is terminated, and control shifts to the sentence after the loop. </tr><tr><td>Flexibility:</td> The <strong> <em>do-while loop</em> </strong> may be utilized in several contexts. It is typically used in cases where a piece of code must be executed at least once, such as <strong> <em>menu-driven programs, input validation,</em> </strong> or <strong> <em>repetitive computations</em> </strong> . </tr><tr><td>Nesting Capability:</td> Similar to other <strong> <em>loop constructs</em> </strong> , the <strong> <em>do-while loop</em> </strong> can be <strong> <em>nested</em> </strong> inside other <strong> <em>loops</em> </strong> or <strong> <em>control structures</em> </strong> to create more complex control flow patterns. It allows for the creation of <strong> <em>nested loops</em> </strong> and the implementation of intricate repetitive tasks. </tr><tr><td>Break and Continue:</td> The break statement can be used within a <strong> <em>do-while loop</em> </strong> to terminate the loop execution and exit the loop prematurely. The <strong> <em>continue statement</em> </strong> can skip the remaining code in the current iteration and jump to the next iteration of the loop. </tr><tr><td>Local Scope:</td> Variables declared inside the <strong> <em>do-while loop</em> </strong> body have local scope and are accessible only within the <strong> <em>loop block.</em> </strong> They cannot be accessed outside the loop or by other loops or control structures. </tr><tr><td>Infinite Loop Control:</td> It is crucial to ensure that the loop's condition is eventually modified within the <strong> <em>loop body</em> </strong> . This modification is necessary to prevent infinite loops where the condition continually evaluates to true. Modifying the condition ensures that the loop terminates at some point. </tr></ul> <hr></=> 説明：
この例では、プログラムは数字のパターンを生成します。 三角形の形状 。の 外側のループ 行を反復処理し、 内側のループ 各行内で反復処理を行い、1 から現在の行番号までの数値を出力します。
while と do while ループの違い
以下は、C の while ループと do-while ループの比較表です。
| 側面 | while ループ | do-while ループ |
|---|---|---|
| 構文 | while (条件) { ... } | do { ... } while (条件); |
| ループ本体の実行 | 実行前に条件がチェックされます。 | 本体は条件の前に実行されます。 |
| 最初の実行 | 条件は最初は true である必要があります。 | 本体は少なくとも 1 回実行されます。 |
| ループ実行 | 0 回以上実行される可能性があります。 | 少なくとも 1 回は実行されます。 |
| 例 | その間（私は<5) { printf(\'%d \', i); i++; }< td> | do { printf('%d ', i); i++; } その間 (私は<5);< td> |
| 一般的な使用例 | ループがまったく実行されない可能性がある場合。 | ループを少なくとも 1 回実行したい場合。 |
While ループ: ループ本体は条件がチェックされる前に実行されます。初期状態の場合 間違い 場合、ループが実行されない可能性があります。
Do-while ループ: の ループ本体 条件が成立する前に少なくとも 1 回実行される チェック済み 。これにより、ループが少なくとも 1 回の反復を完了することが保証されます。
ジャバFX
欲しいときは、 ループ 可能性のある条件に基づいて実行する 間違い 最初に、を使用します while ループ 開始状態に関係なく、ループを少なくとも 1 回実行したい場合は、 do-while ループ。
do whileループの特徴
C の do-while ループには、特定の状況で効果的なプログラミング手法となるいくつかの基本的な特徴があります。 do-while ループの重要な特徴は次のとおりです。