C Program to Find Prime Factors of a Number

In this tutorial, i am going to show you how to find and print prime factors of a number in the c program with the help of for loop, while loop, and recursion.

All C Programs to Find Prime Factors of a Number

  • C Program to Find Prime Factors of a Number Using For Loop
  • C Program to Find Prime Factors of a Number Using While Loop
  • C Program to Find Prime Factors of a Number Using Recursion

C Program to Find Prime Factors of a Number Using For Loop

/* C Program to Find Prime Factors of a Number using For Loop */
 
#include <stdio.h>
 
int main()
{
  	int i, j, Number, isPrime; 
   
  	printf("\n Please Enter any number to Find Factors :  ");
  	scanf("%d", &Number);
 
  	for (i = 2; i <= Number; i++)
   	{
     	if(Number % i == 0)
        {
   			isPrime = 1;
			for (j = 2; j <= i/2; j++)
			{
				if(i % j == 0)
				{
					isPrime = 0;
					break;
				}
			} 
			if(isPrime == 1)
			{
				printf("\n %d is a Prime Factor ", i);
			}	          	
		}
   }
  	return 0;
}

The result of the above c program; as follows:

Please Enter any number to Find Factors :  20
2 is a Prime Factor 
 5 is a Prime Factor 

C Program to Find Prime Factors of a Number Using While Loop

/* C Program to Find Prime factors of a Number using While Loop */
 
#include <stdio.h>
 
int main()
{
  	int Number, i = 1, j, Count; 
 
  	printf("\n Please Enter number to Find Factors  :  ");
  	scanf("%d", &Number);
 
 	while (i <= Number)
   	{
   		Count = 0;
    	if(Number % i == 0)
      	{
      		j = 1;
      		while(j <= i)
      		{
      			if(i % j == 0)
      			{
      				Count++;
				}
				j++;
			}
			if(Count == 2)
			{
				printf("\n %d is a Prime Factor ", i);
			} 
      	}
    	i++;
   	}
 
  	return 0;
}

The result of the above c program; as follows:

Please Enter number to Find Factors  :  50
2 is a Prime Factor 
 5 is a Prime Factor 

C Program to Find Prime Factors of a Number Using Function

#include <stdio.h>
void Find_Prime(int Number)
{ 
  	int i, Count = 0; 
  
  	for (i = 2; i <= Number/2; i++)
   	{
    	if(Number%i == 0)
     	{
       		Count++;
     	} 
   	}
   	if(Count == 0 && Number != 1 )
   	{
   		printf("\n %d is a Prime Number", Number);
   	}
}
void Find_Factors(int Number)
{ 
  	int i; 
  
  	for (i = 1; i <= Number; i++)
   	{
    	if(Number % i == 0)
     	{
     		// Calling Find_Prime Function for every factor
       		Find_Prime(i);
     	} 
   	}
}
int main()
{
  	int i, j, Number, count; 
   
  	printf("\n Please Enter any number to Find it's Prime Factors :  ");
  	scanf("%d", &Number);
 
  	printf("\n Prime Factors of a Given Number are : \n");
	Find_Factors(Number);
  	return 0;
}

The result of the above c program; as follows:

Please Enter any number to Find it's Prime Factors :  100
Prime Factors of a Given Number are : 

 2 is a Prime Number
 5 is a Prime Number

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