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C Program to Print All Prime Numbers between 1 and 100/

C Program to Print All Prime Numbers between 1 and 100

Problem Description

This simple C program prints all the prime numbers between 1 and 100. A Prime number is a natural number greater than 1 that is only divisible by either 1 or itself. All numbers other than prime numbers are known as composite numbers. There are infinitely many prime numbers, here is the list of first few prime numbers
2 3 5 7 11 13 17 19 23 29 31 37....
This C program illustrates the use of nested for loops. The outer for loop iterate from 2 to 100 while the inner loop check the number for prime condition.

C Program to Print All Prime Numbers between 1 and 100 - Source code

/*C program to print all the prime numbers between 1 and 100*/
#include<stdio.h>
int main()
{
int number,j,flag;
printf(" The prime numbers between 1 and 100 : \n");
for(number=2;number<=100;number++)
{
flag=0;
for(j=2;j<=number/2;j++)
{
if(number % j == 0){
flag = 1;
break;
}
}
if(flag==0)
printf("\n %d ",number);
}
return 0;
}

Program Output

The prime numbers between 1 and 100 :
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97

Program Explanation

1. This C program uses nested for loops to find and print all the prime numbers between 1 and 100.
2. The outer loop iterate through 2 to 100, while the inner loop use the modulus operator to check whether the number in current iteration is prime or not. If a prime number is found, the variable flag is set to 1 and the inner loop is existed using the break statement.
3. Otherwise, if flag variable remains zero, the number in current iteration is displayed on the screen as prime number.