C语言程序设计(王立柱）第二章答案 函数

#include<stdio.h>
int Prime(int n);
int main() {
  int n;
  int i;
  int sum = 0;
  printf("Enter an integer:");
  scanf_s("%d", &n);
  for (i = 0; i < n; i++)
    if (Prime(i))
      sum += i;
  printf("Sum of prime from 1 to %d is: %d", n, sum);
  return 0;
}
int Prime(int n) {
  int d;
  if (n == 0 || n == 1)
    return 0;
  for (d = 2; d < n / 2 + 1; d++)
    if (n % d == 0)
      return 0;
  return 1;
}

#include<stdio.h>
int Prime(int n);
int main() {
  int n;
  int num[100];
  int i_num = 0;
  printf("Enter an even number:");
  scanf_s("%d", &n);
  for (int i = 0; i < n; i++)
    if (Prime(i))
      if (Prime(n - i) )
        num[i_num++] = i;
  for (int i = 0; i < i_num; i++)
    printf("%d=%d+%d\n", n, num[i], n - num[i]);
  return 0;
}
int Prime(int n) {
  int d;
  if (n == 0 || n == 1)
    return 0;
  for (d = 2; d < n / 2 + 1; d++)
    if (n % d == 0)
      return 0;
  return 1;
}

#include<stdio.h>
int Sum(int n) {
  printf("sizeof(long long): %d\n", sizeof(long long));
  int sum = 0;
  while (n != 0) {
    sum += n % 10;
    n /= 10;
  }
  return sum;
}
int main() {
  int mima=0;
  int three = 1;
  int n;
  int sum = 0;
  printf("设置密码：");
  scanf_s("%d", &mima);
  printf("输入密码（最多三次）：");
  scanf_s("%d", &n);
  while (three < 4) {
    if (n == mima)
    {
      printf("欢迎使用！\n");
      sum = Sum(mima);
      printf("密码各位之和：%d", sum);
      break;
    }
    if (three < 3)
      printf("输入错误，请重新输入！");
    else
    {
      printf("非法用户！\n"); 
      break;
    }
    three++;
    scanf_s("%d", &n);
  }
  return 0;
}