for statement in C language | Nesting of for in C language | for loop in C Language

for statement is a looping statement used to repeat a set of statements for a specified number of times. Syntax of for statement is:

for(Initialize;Condition;Update)
{
  Statements;
}

for is a predefined keyword of C Language .

Initialize It is the way to store initial value in the control variable which controls how many times loop would execute.

Example

i=1;

Condition: It refers to any relational or logical expression used to check whether the loop should continue or not.

Example

i<=5;

Update: It is the way to increase or decrease the value of control variable.

Example

i++

Statements represents set of instructions which will repeatedly execute as long as condition is true.

Example:

for(k=1;k<=4;k++)

k=1 is the initialization.

k<=4 is the condition.

k++ is the updation.

#include<stdio.h>
int main()
{
int k;
for(k=1;k<=4;k++)
  printf("\n%d",k);
return(0);
}

1
2
3
4

Description of above program

In the program, control variable k has been strored value 1. Value of k is then compared with 4. It is less than 4, so statement printf(“\n%d”,k) gets executed showing value of k i.e. 1.

Then control goes to updation statement k++which increases the value of k by 1. k becomes 2.

Again k<=5 is tested. which is true so printf(“\n%d”,k); gets executed.

Again updation k++ is performed followed by condition k<=4. This process goes on as long as condition is true.

Nesting of for statement in C Language

In this case one for statement is enclosed within another for statement.

#include<stdio.h>
int main()
{
int out,in;
for(out=1;  out<=3;  out++) 
{
      for(in=1;  in<=3;  in++) 
      printf("\n%d,%d",out,in);
}
return(0);
}

1,1
1,2
1,3
2,1
2,2
2,3
3,1
3,2
3,3

Description of above program

In the above program, for one value of outer loop, inner loop will execute completely

for out=1, in  will execute complete i.e. 1,2,3.

for out=2, in will again execute complete i.e. 1,2,3.

Similarly for out=3, in will work complete i.e. 1,2,3.

This process is repeated for next values of out i.e. 2 and 3.