For loop in C

A for loop puts initialization, condition and update in one line. It is very common for counting and array/index problems.

Syntax / Basic Pattern

for (int i = 1; i <= 10; i++) {
printf(“%d “, i);
}

Easy points to remember

Initialization runs once.
Condition is checked before each iteration.
Update runs after the loop body.

⭐ PRACTICE TIP: Type these programs yourself. Change the values and run them again. That is how control statements become easy.

Program 1: Print 1 to 10

#include <stdio.h>
int main(){for(int i=1;i<=10;i++)printf(“%d “,i);return 0;}

OUTPUT
1 2 3 4 5 6 7 8 9 10

Program 2: Even numbers

#include <stdio.h>
int main(){for(int i=2;i<=20;i+=2)printf(“%d “,i);return 0;}

OUTPUT
2 4 6 8 10 12 14 16 18 20

Program 3: Odd numbers

#include <stdio.h>
int main(){for(int i=1;i<=19;i+=2)printf(“%d “,i);return 0;}

OUTPUT
1 3 5 7 9 11 13 15 17 19

Program 4: Sum 1 to 100

#include <stdio.h>
int main(){int s=0;for(int i=1;i<=100;i++)s+=i;printf(“%d”,s);return 0;}

OUTPUT
5050

Program 5: Factorial

#include <stdio.h>
int main(){int f=1;for(int i=1;i<=6;i++)f*=i;printf(“%d”,f);return 0;}

OUTPUT
720

Program 6: Table of 9

#include <stdio.h>
int main(){for(int i=1;i<=10;i++)printf(“%d “,9*i);return 0;}

OUTPUT
9 18 27 36 45 54 63 72 81 90

Program 7: Squares

#include <stdio.h>
int main(){for(int i=1;i<=6;i++)printf(“%d “,i*i);return 0;}

OUTPUT
1 4 9 16 25 36

Program 8: Cubes

#include <stdio.h>
int main(){for(int i=1;i<=5;i++)printf(“%d “,i*i*i);return 0;}

OUTPUT
1 8 27 64 125

Program 9: Reverse count

#include <stdio.h>
int main(){for(int i=10;i>=1;i–)printf(“%d “,i);return 0;}

OUTPUT
10 9 8 7 6 5 4 3 2 1

Program 10: Sum of even

#include <stdio.h>
int main(){int s=0;for(int i=2;i<=20;i+=2)s+=i;printf(“%d”,s);return 0;}

OUTPUT
110

Program 11: Power

#include <stdio.h>
int main(){int p=1;for(int i=1;i<=5;i++)p*=3;printf(“%d”,p);return 0;}

OUTPUT
243

Program 12: Count multiples

#include <stdio.h>
int main(){int c=0;for(int i=1;i<=50;i++)if(i%5==0)c++;printf(“%d”,c);return 0;}

OUTPUT
10

Program 13: Print alphabet

#include <stdio.h>
int main(){for(char c=’A’;c<=’F’;c++)printf(“%c “,c);return 0;}

OUTPUT
A B C D E F

Program 14: Sum odd

#include <stdio.h>
int main(){int s=0;for(int i=1;i<=9;i+=2)s+=i;printf(“%d”,s);return 0;}

OUTPUT
25

Program 15: Fibonacci

#include <stdio.h>
int main(){int a=0,b=1,c;for(int i=1;i<=7;i++){printf(“%d “,a);c=a+b;a=b;b=c;}return 0;}

OUTPUT
0 1 1 2 3 5 8