A ciklushoz C nyelvben az utasítások vagy a program egy részének többszöri ismétlésére szolgál. Gyakran használják az adatstruktúrák, például a tömb és a hivatkozott lista bejárására.
A for ciklus szintaxisa C-ben
A for ciklus szintaxisa c nyelvben az alábbiakban látható:
gimp téglalap rajzolás
for(Expression 1; Expression 2; Expression 3){ //code to be executed } A for ciklus folyamatábrája C-ben
C for ciklus Példák
Lássuk a for ciklus egyszerű programját, amely kiírja az 1-es táblázatot.
#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++){> C Program: Táblázat nyomtatása a megadott számhoz a C for ciklus segítségével
#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
A kifejezés tulajdonságai 1
- A kifejezés a ciklusváltozó inicializálását jelenti.
- Az 1. kifejezésben egynél több változót is inicializálhatunk.
- Az 1. kifejezés nem kötelező.
- C-ben nem deklarálhatjuk a változókat az 1. kifejezésben. Ez azonban kivétel lehet néhány fordítónál.
1. példa
#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++)> 2. példa
#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++)> A kifejezés tulajdonságai 2
- A 2. kifejezés egy feltételes kifejezés. Ellenőrzi, hogy egy adott feltétel teljesül-e. Ha nem, akkor a hurok megszakad.
- A 2. kifejezésnek több feltétele is lehet. A ciklus azonban addig ismétlődik, amíg az utolsó feltétel hamis lesz. Az egyéb feltételeket nyilatkozatként kezeljük.
- A 2. kifejezés nem kötelező.
- A 2. kifejezés képes ellátni az 1. és a 3. kifejezés feladatát. Vagyis inicializálhatjuk a változót, valamint magában a 2. kifejezésben frissíthetjük a ciklusváltozót.
- A 2. kifejezésben nulla vagy nem nulla értéket adhatunk át. C-ben azonban minden nullától eltérő érték igaz, a nulla pedig alapértelmezés szerint hamis.
1. példa
konvertálja a java objektumot json-ba
#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++)> 2. példa
#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++)> 3. példa
#include int main() { int i; for(i=0;;i++) { printf('%d',i); } } Kimenet
infinite loop
A kifejezés tulajdonságai 3 - A 3. kifejezés a ciklusváltozó frissítésére szolgál.
- Egyszerre több változót is frissíthetünk.
- A 3. kifejezés nem kötelező.
1. példa
Linux könyvtár átnevezése
#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)> Hurok test
A kapcsos zárójelek {} a hurok hatókörének meghatározására szolgálnak. Ha azonban a ciklus csak egy utasítást tartalmaz, akkor nem kell kapcsos zárójeleket használnunk. Test nélküli hurok lehetséges. A kapcsos zárójelek blokk elválasztóként működnek, azaz a cikluson belül deklarált értékváltozó csak arra a blokkra érvényes, azon kívül nem. Tekintsük a következő példát.
#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++)> Infinitivus a ciklushoz C-ben
Ahhoz, hogy egy for ciklus végtelen legyen, nem kell semmilyen kifejezést megadnunk a szintaxisban. Ehelyett két pontosvesszőt kell megadnunk a for ciklus szintaxisának érvényesítéséhez. Ez végtelen for ciklusként fog működni.
#include void main () { for(;;) { printf('welcome to javatpoint'); } } Ha ezt a programot futtatja, a fenti utasítás végtelenül sokszor fog megjelenni.