Break,continue and goto in c programing | My CS Tutorial

Loop Control Statements

Loop control statements change execution from its normal sequence. When
execution leaves a scope, all automatic objects that were created in that scope are destroyed.
C supports the following control statements.

Control Statement and Description

break statement   -   Terminates the loop or switch statement and
transfers execution to the statement immediately
following the loop or switch.

continue statement   -   Causes the loop to skip the remainder of its body and
immediately retest its condition prior to reiterating.

goto statement   -   Transfers control to the labeled statement.

break Statement 

The break statement in C programming has the following two usages:

When a break statement is encountered inside a loop, the loop is
immediately terminated and the program control resumes at the next
statement following the loop.

It can be used to terminate a case in the switch statement (covered in
the next chapter).

If you are using nested loops, the break statement will stop the execution of the
innermost loop and start executing the next line of code after the block.

Syntax

The syntax for a break statement in C is as follows:

break;

Flow Diagram

Example

#include <stdio.h>
int main ()
{
 /* local variable definition */
 int a = 10;
 /* while loop execution */
 while( a < 20 )
 {
 printf("value of a: %d\n", a);
 a++;
 if( a > 15)
 {
 /* terminate the loop using break statement */
 break;
 }
 }
return 0;
}


When the above code is compiled and executed, it produces the following result:
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15

continue Statement

The continue statement in C programming works somewhat like the break
statement. Instead of forcing termination, it forces the next iteration of the loop
to take place, skipping any code in between.
For the for loop, continue statement causes the conditional test and increment
portions of the loop to execute. For the while and do...while loops, continue
statement causes the program control to pass to the conditional tests.

Syntax

The syntax for a continue statement in C is as follows:

continue;

Flow Diagram

Example

#include <stdio.h>

int main ()
{
 /* local variable definition */
 int a = 10;
 /* do loop execution */
 do
 {
 if( a == 15)
 {
 /* skip the iteration */
 a = a + 1;
 continue;
 }
 printf("value of a: %d\n", a);
 a++;

 }while( a < 20 );
return 0;
}


When the above code is compiled and executed, it produces the following result:
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 16
value of a: 17
value of a: 18
value of a: 19

goto Statement

A goto statement in C programming provides an unconditional jump from the
‘goto’ to a labeled statement in the same function.
NOTE: Use of goto statement is highly discouraged in any programming
language because it makes difficult to trace the control flow of a program,
making the program hard to understand and hard to modify. Any program that
uses a goto can be rewritten to avoid them.

Syntax

The syntax for a goto statement in C is as follows:

goto label;
..
.
label: statement;


Here label can be any plain text except C keyword and it can be set anywhere in
the C program above or below to goto statement.

Flow Diagram

Example

#include <stdio.h>
int main ()
{
 /* local variable definition */
 int a = 10;
 /* do loop execution */
 LOOP:do
 {
 if( a == 15)
 {
 /* skip the iteration */
 a = a + 1;
 goto LOOP;
 }
 printf("value of a: %d\n", a);
 a++;

 }while( a < 20 );
return 0;
}


When the above code is compiled and executed, it produces the following result:
value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 16
value of a: 17
value of a: 18
value of a: 19

The Infinite Loop

A loop becomes an infinite loop if a condition never becomes false. The for loop
is traditionally used for this purpose. Since none of the three expressions that
form the ‘for’ loop are required, you can make an endless loop by leaving the
conditional expression empty.

#include <stdio.h>
int main ()
{
 for( ; ; )
 {
 printf("This loop will run forever.\n");
 }
 return 0;
}


When the conditional expression is absent, it is assumed to be true. You may
have an initialization and increment expression, but C programmers more
commonly use the for(;;) construct to signify an infinite loop.

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Created by-- HARSH CHAUHAN