for loop in C ?

A for loop is a control statement using which the programmer can give instructions to the computer to execute a set of statement repeatedly as long as specified condition is satisfied. It is required to specify how many times a set of statements have to be executed, it is also called counter controlled loop.

How for Loop Works

• Step 1:-
  The initialization statement is executed only once i.e exp1.
• Step 2:-
  Then, the test expression is evaluated. If the test expression is evaluated to false, then the for loop gets terminated and the control comes out of the loop.
• Step 3:-
  the next step the condition(Test Expression i.e exp2) is checked if the test expression is evaluated to true, statements inside the body of the for loop are executed,
• Step 4:-
  After successful execution of statements inside the body of the loop, the update expression (i.e exp3) also called counter variable is updated. incremented or decremented, depending on the operation (++ or –).
• Step 5:-
  Again the test expression is evaluated.

Example with dry Run Concepts

 #include<stdio.h>
 #include<conio.h>
 void main()
 {
 int i; 
 for(i = 1; i <=5 ; i++)
 {     
 printf(“%d\n”, i );     
 }
 getch();
 }

Program Explanation

• Step 1:-
  We declared integer variables called i. The initialization statement is executed only once i.e i=1
• Step 2:-
  Then, the test expression is evaluated. i.e i is less than or equals to 5 or not (i <=5 ) hear condition is true so statements inside the body of the for loop are executed, and it will print the value of i i.e 1
• Step 4:-
  After successful execution of statements inside the body of the loop, the update expression (i.e i++) means it incremented by 1 now the value of i is 2
• Step 5:-
  Again the test expression is evaluated. and repeat step 2 till the condition is false
• Step 5:-
  when the condition is false means the value of i will be 6 then for loop gets terminated and the control comes out of the loop.

 #include<stdio.h>
 #include<conio.h>
 void main()
 {
   int i;
   printf("Enter Number);
   scanf("%d",&n);   
   for(i = 1; i <=n ; i++)
   {     
      s=s+i;    
   }
   printf(“Sum of 1 to n is:-%d\n”,s); 
 getch();
 }

Program Explanation

• Step 1:-
  We declared three integer variables called i,s and n.
• Step 2:-
  hear we initialization s=0 because we will have to sum from 1 to n so it not initialization garwage value
• Step 3:-A Message will give for entering their own values for n :- Enter a Number:- 5
• Step 4:-
  
The initialization statement is executed only once i.e i=1
• Step 5:-
  Then, the test expression is evaluated. i.e i is less than or equals to 5 or not (i <=5 ) hear condition is true so statements inside the body of the for loop are executed, and it will print the value of s after assign value s=i+s
• Step 6:-
  After successful execution of statements inside the body of the loop, the update expression (i.e i++) means it incremented by 1 now the value of i
• Step 7:-
  Again the test expression is evaluated. and repeat step 2 till the condition is false
• Step 8:-
  When the condition is false means the value of i will be 6 then for loop gets terminated and the control comes out of the loop.
• Step 9:-
  and print value of s i.e Sum of 1 to n is 15

 #include<stdio.h>
 #include<conio.h>
 void main()
 {
  int i,t,n;
  printf("Enter a Number");
  scanf("%d",&n); 
  for(i = 1; i <=10 ; i++)
  {     
     t=t*n;
    printf(“%d\n”, t );     
  }
 getch();
 }

Program Explanation

• Step 1:-
  We declared three integer variables called i,t and n.
• Step 2:-A Message will give for entering their own values for n :- Enter a Number:- 2
• Step 3:-
  
The initialization statement is executed only once i.e i=1
• Step 2:-
  Then, the test expression is evaluated. i.e i is less than or equals to 10 or not (i <=10 ) hear condition is true so statements inside the body of the for loop are executed, and it will print the value of t after assign value i*n
• Step 4:-
  After successful execution of statements inside the body of the loop, the update expression (i.e i++) means it incremented by 1 now the value of i is 2
• Step 5:-
  Again the test expression is evaluated. and repeat step 2 till the condition is false
• Step 5:-
  when the condition is false means the value of i will be 11 then for loop gets terminated and the control comes out of the loop.

C for loop MCQ Question

1. Loops or Repetition block executes a group of statements repeatedly.
2. Loop is usually executed as long as a condition is met.
3. Loops usually take advantage of Loop Counter
4. All the above.

1. for
2. while
3. do while
4. All the above.

1. break
2. exit
3. if
4. else

1. keyword
2. identifier
3. variable
4. All the above.

1. increment or decrement operator
2. identifier
3. variable
4. All the above.

int main()
{
   int i = 0;
   for (i=0; i<20; i++)
   {
     switch(i)
     {
       case 0:
         i += 5;
       case 1:
         i += 2;
       case 5:
         i += 5;
       default:
         i += 4;
         break;
     }
     printf("%d  ", i);
   }
   return 0;
}

1. 16 21
2. 66 45
3. 65 69
4. error