C Program Flow - C Programming

Online Reference

C REFERENCE

RAPID TABLES

Home > Programming > C Reference > Program Flow

C Reference - Program flow keywords
Name Description
if-else do if condition is true
switch-case-default branch to const integer case that match switch expression or to default when no match. then falls through.
for do loop when condition is true
while do loop when condition is true
do-while do loop when condition is true, do at least once
break exit from switch, for, while, do
continue branch to next loop iteration of for, while , do
goto branch to label
return exit to calling function and return value

if-else
Syntax:
if( condition )
   statement1
else
   statement2
Description:
If condition is true do statement1.
If condition is not true do statement2.
Example:
if( a>0 )
   x = x+5;
else
   x = x-5;

if( a>0 )
   x += 10;
else if( a<0 )
   x -= 10;
else
   x = 0;

switch-case-default
Syntax:
switch( variable )
{
   case const1:
      statement1
      break;
   case const2:
   case const3:
      statement2
      break;
   .
   .
   default:
      statement3
}
Description:
If variable is equal to const1 - do statement1
If variable is equal to const2 or const3 - do statement2
Otherwise do statement3
Example:
int state;

switch( state )
{
   case 0:
   case 1:
      x = x+5;
      break;

   case 2:
      x = x-5;
      break;

   default:
      x = 0;
}

for
Syntax:
for(init_statement; stop_condition; expression)
   statement
Description:
Do statement while stop condition is not met.
Example:
/* print x values from 0 to 99 */
for( x=0; x<100; x++ )
{
   printf("x=%d\n",x);
}

while
Syntax:
while( condition )
   statement
Description:
Do statement while condition is true.
Example:
/* print x values from 0 to 99 */
x = 0;
while( x<100 )
{
   printf("x=%d\n",x);
   x++;
}

do-while
Syntax:
do
   statement
while( condition );
Description:
Do statement while condition is true.
Do at least once.
Example:
/* print x values from 0 to 99 */
x = 0;
do {
   printf("x=%d\n",x);
   x++;
} while( x<100 )

break
Syntax:
break;
Description:
Break from current block.
Example1:
Switch( x ) {
   case 0:
      y = x;
      break;
   case 1:
      y = 2*x;
}
Example2:
while(1) {
   if( x>y )
      break;
}

continue
Syntax:
continue;
Description:
Continue execution in next loop iteration.
Example:
for(i=0; i<N; i++)
{
   if( a[i] > 0 )
       continue;
   sum = sum+a[i];
}

goto
Syntax:
goto label;
Description:
Jump to specified label.
Example:
goto MYLABEL;
:
:
MY_LABEL:

return
Syntax:
return expression;
Description:
Return from function with return value.
Examples:
/* return with no value (void) */
return;

return 0;

return (x*y);