break and continue statements alter the normal flow of
control. Some programmers feel that these statements violate the norms
of structured programming so they only use break in a switch structure
and never use continue.
The break statement
The break statement, when executed in one of the repetition structures
(for, while or do/while), causes immediate exit from the structure.
Execution continues with the first statement after the loop.
while loop with a break statement
/*
* File: addlist.c
* ---------------
* This program adds a list of numbers. The end of the
* input is indicated by entering 0 as a sentinel value.
*/
#include <stdio.h>
main()
{
int value, total;
/* Give instructions to the user */
printf("This program adds a list of numbers.\n");
printf("Signal end of list with a 0.\n");
/* Initialize total */
total = 0;
/* Get integers from the user until a 0
is entered, keeping a running total */
while (1)
{
printf("Enter an integer, 0 to end : ");
scanf ("%d", &value);
if (value == 0)
{
break;
}
total += value;
}
/* Print the total */
printf("The total is %d\n", total);
}
Output
lassie% cc addlist.c
lassie%
lassie% a.out
This program adds a list of numbers.
Signal end of list with a 0.
Enter an integer, 0 to end : 89
Enter an integer, 0 to end : 72
Enter an integer, 0 to end : 3
Enter an integer, 0 to end : 4
Enter an integer, 0 to end : 10
Enter an integer, 0 to end : 123
Enter an integer, 0 to end : 0
The total is 301
lassie%
The continue statement
The continue statement, when executed in one of the repetition structures
(for, while or do/while), causes the remaining statements in the body of the
loop to be skipped and the loop to start its next iteration.
example using a continue statement
/*
* File: even.c
* ---------------
* This program prints the even numbers from 1 to 10. It
* illustrates the continue statement, but is not
* considered to be good code.
*/
#include <stdio.h>
main()
{
int num;
/* Give instructions to the user */
printf("This program prints even numbers\n");
printf("between 1 and 10.\n\n");
/* count from 1 to 10 */
for (num = 1; num <= 10; num++)
{
/* skip printing odd numbers */
if (num % 2 != 0)
{
continue;
}
/* will only print even numbers */
printf("%d ", num);
}
printf("\n");
}
Output
lassie% cc even.c
lassie%
lassie% a.out
This program prints even numbers
between 1 and 10.
2 4 6 8 10
lassie%