Le boucle for en langage C est utilisé pour itérer plusieurs fois les instructions ou une partie du programme. Il est fréquemment utilisé pour parcourir les structures de données telles que le tableau et la liste chaînée.
Syntaxe de la boucle for en C
La syntaxe de la boucle for en langage C est donnée ci-dessous :
printemps et printemps mvc
for(Expression 1; Expression 2; Expression 3){ //code to be executed } Organigramme de la boucle for en C
Exemples de boucles C for
Voyons le programme simple de la boucle for qui imprime le tableau de 1.
#include int main(){ int i=0; for(i=1;i<=10;i++){ printf('%d
',i); } return 0; < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 5 6 7 8 9 10 </pre> <h3>C Program: Print table for the given number using C for loop</h3> <pre> #include int main(){ int i=1,number=0; printf('Enter a number: '); scanf('%d',&number); for(i=1;i<=10;i++){ printf('%d
',(number*i)); } return 0; < pre> <p> <strong>Output</strong> </p> <pre> Enter a number: 2 2 4 6 8 10 12 14 16 18 20 </pre> <pre> Enter a number: 1000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 </pre> <h3>Properties of Expression 1</h3> <ul> <li>The expression represents the initialization of the loop variable.</li> <li>We can initialize more than one variable in Expression 1.</li> <li>Expression 1 is optional.</li> <li>In C, we can not declare the variables in Expression 1. However, It can be an exception in some compilers.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int a,b,c; for(a=0,b=12,c=23;a<2;a++) { printf('%d ',a+b+c); } < pre> <p> <strong>Output</strong> </p> <pre> 35 36 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i=1; for(;i<5;i++) { printf('%d ',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf('%d ',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf('%d %d %d
',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf('%d %d
',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf('%d ',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)></pre></2;a++)></pre></=10;i++){></pre></=10;i++){> Programme C : imprimer le tableau pour le nombre donné en utilisant la boucle C for
#include int main(){ int i=1,number=0; printf('Enter a number: '); scanf('%d',&number); for(i=1;i<=10;i++){ printf(\'%d
\',(number*i)); } return 0; < pre> <p> <strong>Output</strong> </p> <pre> Enter a number: 2 2 4 6 8 10 12 14 16 18 20 </pre> <pre> Enter a number: 1000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 </pre> <h3>Properties of Expression 1</h3> <ul> <li>The expression represents the initialization of the loop variable.</li> <li>We can initialize more than one variable in Expression 1.</li> <li>Expression 1 is optional.</li> <li>In C, we can not declare the variables in Expression 1. However, It can be an exception in some compilers.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int a,b,c; for(a=0,b=12,c=23;a<2;a++) { printf(\'%d \',a+b+c); } < pre> <p> <strong>Output</strong> </p> <pre> 35 36 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i=1; for(;i<5;i++) { printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)></pre></2;a++)></pre></=10;i++){> Enter a number: 1000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
Propriétés de l'expression 1
- L'expression représente l'initialisation de la variable de boucle.
- Nous pouvons initialiser plus d'une variable dans l'expression 1.
- L'expression 1 est facultative.
- En C, on ne peut pas déclarer les variables dans l'expression 1. Cependant, cela peut constituer une exception dans certains compilateurs.
Exemple 1
#include int main() { int a,b,c; for(a=0,b=12,c=23;a<2;a++) { printf(\'%d \',a+b+c); } < pre> <p> <strong>Output</strong> </p> <pre> 35 36 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i=1; for(;i<5;i++) { printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)></pre></2;a++)> Exemple 2
#include int main() { int i=1; for(;i<5;i++) { printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)> Propriétés de l'expression 2
- L'expression 2 est une expression conditionnelle. Il vérifie qu’une condition spécifique doit être remplie. Si ce n'est pas le cas, la boucle est terminée.
- L'expression 2 peut avoir plusieurs conditions. Cependant, la boucle va itérer jusqu'à ce que la dernière condition devienne fausse. Les autres conditions seront traitées comme des déclarations.
- L'expression 2 est facultative.
- L'expression 2 peut effectuer la tâche de l'expression 1 et de l'expression 3. Autrement dit, nous pouvons initialiser la variable ainsi que mettre à jour la variable de boucle dans l'expression 2 elle-même.
- Nous pouvons transmettre une valeur nulle ou non nulle dans l'expression 2. Cependant, en C, toute valeur non nulle est vraie et zéro est faux par défaut.
Exemple 1
base de données
#include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)> Exemple 2
#include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\\'%d %d %d
\\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\\'%d %d
\\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\\'%d \\',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)> Exemple 3
#include int main() { int i; for(i=0;;i++) { printf('%d',i); } } Sortir
infinite loop
Propriétés de l'expression 3 - L'expression 3 est utilisée pour mettre à jour la variable de boucle.
- Nous pouvons mettre à jour plusieurs variables en même temps.
- L'expression 3 est facultative.
Exemple 1
couleurs Java
#include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\\'%d %d
\\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\\'%d \\',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)> Corps en boucle
Les accolades {} sont utilisées pour définir la portée de la boucle. Cependant, si la boucle ne contient qu’une seule instruction, nous n’avons pas besoin d’utiliser d’accolades. Une boucle sans corps est possible. Les accolades fonctionnent comme un séparateur de bloc, c'est-à-dire que la variable de valeur déclarée à l'intérieur de la boucle for n'est valide que pour ce bloc et non à l'extérieur. Considérez l'exemple suivant.
#include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\\'%d \\',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)> Infinitif for boucle en C
Pour rendre une boucle for infinie, nous n'avons besoin de donner aucune expression dans la syntaxe. Au lieu de cela, nous devons fournir deux points-virgules pour valider la syntaxe de la boucle for. Cela fonctionnera comme une boucle for infinie.
#include void main () { for(;;) { printf('welcome to javatpoint'); } } Si vous exécutez ce programme, vous verrez ci-dessus une instruction infinie.