Program Transfer Control Statements

break Statement

The break statement is used with in switch statement to transfer program control out of switch statement after executing a set  of statements mentioned in a particular case.

break statement can also be used in looping statements to transfer program control out of the loop. This will help to terminate a loop when a particular condition is met.

Example:

This program will check whether the given number contain digit 0.It is noted  that when the number contain first 0, we can stop doing the process and print that the number contains 0.There is no point in continuing the loop and hence computation time can be saved.

#include <stdio.h>
main() 

{
    int n,digit;
    printf("Enter an integer: ");
    scanf("%d", &n);
    while (n != 0) {
        digit= n % 10;
        n = n/10;

        if (digit==0) {
               printf("number contains 0\n");
                      break;
                      }
          }
     }

o/p
Enter an integer:23045

number contains zero

continue statement

continue statement is used inside loop to skip the execution of remaining statement and continue the iteration.

Example:

The following program will print numbers from 1 to 15 except the  numbers which are divisible by 3. When the number is divisible by 3, the loop is continued skipping the print statement. The continue statement will make the  program control to jump to the beginning of the loop .

#include <stdio.h>
main()
{
  int i;
    for(i=1;i<=15;i++)
    {
     if(i%3==0)
            continue;
     printf("%d\n",i);
    }
     
}

o/p
1
2

4

5

7

8

10

11

13

14

Difference Between break and continue in C

S.No.	break	continue
1.	break statement is used in switch and loops.	continue statement is used in loops only.
2.	When break is encountered the switch or loop execution is immediately stopped.	When continue is encountered, the statements after it are skipped and the loop control jump to next iteration.
3.	Example: #include<stdio.h> main() {    int i;   for(i=0;i<5;++i)  {        if(i==3)                break;        printf(“%d “,i);   }  Output: 0 1 2	Example: #include<stdio.h> main(){                 int i;                 for(i=0;i<5;++i)               {                      if(i==3)                              continue;                   printf(“%d “,i);                 }    }  Output: 0 1 2 4

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. Code can get confusing very quickly when it takes arbitrary paths and jumps from place to place.Any program that uses a goto can be rewritten to avoid them. 

Syntax of goto statement

goto label;
... .. ...
... .. ...
... .. ...
label:
statement;

 

The label is an identifier. When goto statement is encountered, control of the program jumps to label: and starts executing the code from there. The label can be set above or below the goto statement.

Example:

The following will find sum of numbers entered by user till the user enters a negative number.When a negative number is entered, the program control is transferred to the statement with label end, otherwise the number will be added to sum and control will be transferred to the statement labelled begin.

#include <stdio.h>
main()
{
  int number,sum=0;
   
 begin:  printf("Enter numbers give -ve number to stop\n");
        scanf("%d",&number);
         if( number <0) goto end;
        sum=sum+number;

   goto begin;

      end:printf("sum=%d\n",sum);
}

exit function

 

exit() is useful for terminating a program upon having discovered some error which prevents the program from continuing to execute normally. It’s prototype as follows, 

void exit(int status);

status argument passed to exit() is returned to O.S. to inform that whether or not program succeeded normally. Notice that this status argument is as same as status main() passes to O.S. Pre defined symbols EXIT_SUCCESS and EXIT_FAILURE are used to pass successful and failure status to O.S respectively. EXIT_SUCCESS is represented with 0 and EXIT_FAILURE with value 1.exit() function is prototyped in stdlib.h header file.

 

Example

the following program will find root of a number.If the given number is -ve the program is terminated with exit(1) function.

 

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
main()
{
  int n;
  printf("enter a number\n");
  scanf("%d",&n);
  if (n<0) {
printf("cant find root of -ve numbers\n");
printf("terminating the program\n");
         exit(1);
         }
 printf("sqrt=%f\n",sqrt(n));
}