参考：

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include<math.h>

void Positive_integer_disintegrant(int n)
{
    int i = 2, m;
    m = n;
    printf("%d = ", n);
    while (i <=(n/2)) {
        if (m%i == 0) {
            printf("%d", i);
            m = m / i;
            if (m != 1) {
                printf(" * ");
            }
        }
        if (m%i != 0) {
            i++;
        }
    }
}

int main(void)
{
    int n;
    printf("正整数分解质因数\n");
    scanf("%d", &n);
    Positive_integer_disintegrant(n);
    //system("pause");
    return 0;
}

参考方法：

#include<stdio.h>
int main(void)
{
    int n,count = 1,num,i = 2;
    printf("请输入整数：");
    scanf("%d",&n);
    num = n;
    while(i < num)
    {
        if(n%i == 0)
        {
            if(count == 1)
                printf("%d=%d",n,i);
            else
                printf("*%d",i);
            count++;
            n = n/i;
        }
        else
            i++;
    }
    return 0;
}

参考方法：

#include<stdio.h>
#include <math.h>

int main() 
{
    int i = 2, m, sq;
    printf("请输入整数：");
    scanf("%d", &m);
    sq = sqrt(m);  //这个可以参考下质数的筛选方式
    while (i <= sq)
    {
        if (m % i == 0) 
        {
            printf("%d", i);
            m /= i;
            if (m != 1)
                printf("*");
        }
        else
            i++;
    }
    if (m != 1)
        printf("%d", m);
    while (getchar() != EOF)
    {
    }
}