## Prime Number Program in C (or) Prime Number in C.

Prime Number: A number that is divisible only by itself and 1 is called Prime number.

Example of prime numbers : 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, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 etc.

### Prime Number Program in C (or) Prime Number in C.

Prime number program in c using while loop:
#include<stdio.h>
int main()
{
int i,j,k;
printf("Enter a number: ");
scanf("%d",&i);
k=0;
j=2;
while(j <= i/2)
{
if(i%j == 0)
{
k=1;
break;
}
j++;
}
if(k==0)
printf(" Entered number is Prime Number.");
else
printf("Entered number is Not Prime Number.");
return 0;

}
Output:
Enter a number: 7

Entered number is Prime Number.

### Prime Number Program in C (or) Prime Number in C.

Prime number using for loop:

Prime number using in c using for loop:
#include<stdio.h>
int main()
{
int i,j,k;
printf("Enter a number: ");
scanf("%d",&i);
k=0;
for(j=2;j <= i/2;j++)
{
if(i%j == 0)
{
k=1;
break;
}
}
if(k==0)
printf("Prime Number");
else
printf("Not Prime Number");
return 0;

}
Output:
Enter a number: 7
Prime Number

### Prime number program to print from 1 to 100.

C program to print numbers from 1 to 100:
#include<stdio.h>
int main()
{
int limit = 100;
printf("Prime numbers between 1 and 100 are: ");
for(int i = 2; i < limit; i++)
{
int flag = 0;
for(int j=2;j < i;j++)
{
if(i%j==0)
{
flag = 1;
break;
}
}
if(flag ==0)
printf("%d ",i);
}
return 0;
}
Output:
Prime numbers between 1 and 100 are: 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.

### Prime number program to print from 1 to N.

C program to print numbers from 1 to N:
#include<stdio.h>
int main(){
int i,j,count,k;
printf("Enter max range: ");
scanf("%d",&k);
for(i = 1;i<=k;i++)
{
count = 0;
for(j=2;j<=i/2;j++){
if(i%j==0){
count++;
break;
}
}
if(count==0 && i!= 1)
printf("%d ",i);
}
return 0;

}
Output:
Enter max range: 70

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67.

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