Loops in C:
Loop:-it is a block of statement that performs set of instructions. In loops
Repeating particular portion of the program either a specified number of time or
until a particular no of condition is being satisfied.
There are three types of loops in c
1.While loop
2.do while loop
3.for loop
While loop:
Syntax:-
while(condition)
{
Statement 1;
Statement 2;
}
Or
while(test condition)
Statement;
The test condition may be any expression .when we want to do something a fixed
no of times but not known about the number of iteration, in a program then while
loop is used.
Here first condition is checked if, it is true body of the loop is executed else, If
condition is false control will be come out of loop.
Example:-
/* wap to print 5 times welcome to C” */
#include <stdio.h>
void main()
{
int p=1;
While(p<=5)
{
printf(“Welcome to C\n”);
P++;
}
}
Output:
Welcome to C
Welcome to C
Welcome to C
Welcome to C
Welcome to C
So as long as condition remains true statements within the body of while loop will
get executed repeatedly.
do while loop:
This (do while loop) statement is also used for looping. The body of this loop may
contain single statement or block of statement. The syntax for writing this
statement is:
Syntax:-
Do
{
Statement;
}
while(condition);
Example:-
#include <stdio.h>
void main()
{
int X=4;
do
{
Printf(“%d”,X);
X=X+1;
}
whie(X<=10);
Printf(“ ”);
}
Output: 4 5 6 7 8 9 10
Here firstly statement inside body is executed then condition is checked. If the
condition is true again body of loop is executed and this process continue until the
condition becomes false. Unlike while loop semicolon is placed at the end of
while.
There is minor difference between while and do while loop, while loop test the
condition before executing any of the statement of loop. Whereas do while loop
test condition after having executed the statement at least one within the loop.
If initial condition is false while loop would not executed it’s statement on other
hand do while loop executed it’s statement at least once even If condition fails for
first time. It means do while loop always executes at least once.
Notes:
Do while loop used rarely when we want to execute a loop at least once.
for loop:
In a program, for loop is generally used when number of iteration are known in
advance. The body of the loop can be single statement or multiple statements. Its
syntax for writing is:
Syntax:-
for(exp1;exp2;exp3)
{
Statement;
}
Or
for(initialized counter; test counter; update counter)
{
Statement;
}
Here exp1 is an initialization expression, exp2 is test expression or condition and
exp3 is an update expression. Expression 1 is executed only once when loop
started and used to initialize the loop variables. Condition expression generally
uses relational and logical operators. And updation part executed only when after
body of the loop is executed.
Example:-
void main()
{
int i;
for(i=1;i<10;i++)
{
Printf(“ %d ”, i);
}
}
Output:-1 2 3 4 5 6 7 8 9
Nesting of loop:
When a loop written inside the body of another loop then, it is known as nesting of
loop. Any type of loop can be nested in any type such as while, do while, for. For
example nesting of for loop can be represented as :
void main()
{
int i,j;
for(i=0;i<2;i++)
for(j=0;j<5; j++)
printf(“%d %d”, i, j);
}
Output:
i=0
j=0 1 2 3 4
i=1
j=0 1 2 3 4
Very helpful ❤️❤️❤️
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