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

 

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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;

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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; }

 

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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); }

 

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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++; }

 

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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 )

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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; }

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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]; }

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goto

Syntax:

goto label;

Description:

Jump to specified label.

Example:

goto MYLABEL; : : MY_LABEL:

 

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return

Syntax:

return expression;

Description:

Return from function with return value.

Examples:

/* return with no value (void) */ return;   return 0;   return (x*y);