C语言显示两个区间内素数的程序

显示两个区间之间的素数

#include <stdio.h>

int main() {
   int low, high, i, flag;
   printf("Enter two numbers(intervals): ");
   scanf("%d %d", &low, &high);
   printf("Prime numbers between %d and %d are: ", low, high);

   // iteration until low is not equal to high
   while (low < high) {
      flag = 0;

      // ignore numbers less than 2
      if (low <= 1) {
         ++low;
         continue;
      }

      // if low is a non-prime number, flag will be 1
      for (i = 2; i <= low / 2; ++i) {

         if (low % i == 0) {
            flag = 1;
            break;
         }
      }

      if (flag == 0)
         printf("%d ", low);

      // to check prime for the next number
      // increase low by 1
      ++low;
   }

   return 0;
}

输出

Enter two numbers(intervals): 20 
50
Prime numbers between 20 and 50 are: 23 29 31 37 41 43 47

在此程序中，while 循环迭代 (high-low-1) 次。

在每次迭代中，都会检查low 是否为素数，并将low 的值增加1，直到low 等于high。

访问此页面了解如何 检查一个数字是否为素数。

如果用户先输入较大的数字，则上述程序将无法按预期工作。您可以通过 交换数字 来解决此问题。

当先输入较大的数字时显示素数

#include <stdio.h>

int main() {
   int low, high, i, flag, temp;
   printf("Enter two numbers(intervals): ");
   scanf("%d %d", &low, &high);

   // swap numbers if low is greather than high
   if (low > high) {
      temp = low;
      low = high;
      high = temp;
   }

   printf("Prime numbers between %d and %d are: ", low, high);
   while (low < high) {
      flag = 0;

      // ignore numbers less than 2
      if (low <= 1) {
         ++low;
         continue;
      }

      for (i = 2; i <= low / 2; ++i) {
         if (low % i == 0) {
            flag = 1;
            break;
         }
      }
      if (flag == 0)
         printf("%d ", low);
      ++low;
   }

   return 0;
}

访问此页面了解如何 通过创建用户定义的函数来显示两个区间内的所有素数