comparision of looping statement in c

1. Comparison of the loop
control structures
Prakash Khaire
B V Patel Inst. of BMC & IT, GopalVidyanagar

2. for while do…while
A for loop is used to A while loop is used to A do while loop is used to
execute and repeat a execute and repeat a execute and repeat a
statement block depending statement block depending statement block depending
on a condition which is on a condition which is on a condition which is
evaluated at the beginning evaluated at the beginning evaluated at the end of the
of the loop. of the loop. loop.
Example : Example Example
for(i=1; i<=5; i++) i=1; i=1;
{ while(i <=5 ) do
s = s + i; { {
p = p * i; s = s + i; s = s + i;
} p = p * i; p = p * i;
i++; i++;
} }while(i<=5);

3. for while do…while
A variable value isA variable value isA variable value is
initialized at the beginninginitialized at the beginninginitialized before the loop
of the loop and is used inor before the loop and isor assigned inside the loop
the condition. used in the condition. is used in the condition.
A statement to change theA statement to change theA statement to change the
value of the condition or tovalue of the condition or tovalue of the condition or to
increment the value of theincrement the value of theincrement the value of the
variable is given at thevariable is given inside thevariable is given inside the
beginning of the loop. loop. loop.
The statement block will The statement block willThe statement block will
not be executed when thenot be executed when thenot be executed when the
value of the condition isvalue of the condition isvalue of the condition is
false. false. false, but the block is
executed at least once
irrespective of the value of
the condition

4. for while do…while
A for loop is commonlyA while loop is also widelyA do-while loop is used in
used by manyused by manysome cases where the
programmers. programmers. condition need to be
checked at the end of the
loop.

5. break Statement
* The break statement, when executed in a
while, for, do/while, or switch structure,
causes immediate exit for that structure.
* Program execution continues with the first
statement after the structure.
* Common uses of the break statement are
to escape early from a loop, or to skip the
remainder of a switch structure

6. Continue Statement
* The continue statement, when executed
in a while, for, or do/while structure, skips
the remaining statements in the body of
that structure, and proceeds with the next
iteration of the loop.
* In while and do/while structures, the loop-
continuation test is evaluated
immediately after the continue statement
is executed.
* In the for structure, the increment
expression is executed, then the loop-
continuation test is evaluated.

7. #include <stdio.h>
#include <stdlib.h>
int main ()
{ unsigned x;
x = 0;
while (x < 10)
{
++x;
if (x % 2 == 0)
{
continue;
}
printf ("%i is an odd number.n", x);
}
return 0;
}