Question

我正在运行此程序

#include <stdio.h>
int main ()
{
  int n;
  int a = 1;
  int b = 2;
  int product;
  int i;

  printf("How many numbers of the sequence would you like \n");
  scanf("%d",&n);

  for (i=0;i<n;i++)
  {
    printf("%d\n",a);
    product = a * b;
    a = b;
    b = product;
  }

   return 0;
}

当我输入n = 3时，结果是1 2 2
为什么？我的意思是让它显示1 2 4，我做错了什么？为什么打印1 2 2。

Answer 1

为什么要打印1 2 2。

printf("%d\n",a);处的逐步跟踪：

i  a  b  product
0  1  2  ?
1  2  2  2
2  2  4  4
3  4  8  8
4  8  32 32

Answer 2

1 2 2因为您在每次迭代中打印a而不是product并且a的值为 -

  1st iteration a=1
  2nd iteration a=2        // a=b and b=2 i.e a=2
  3rd iteration a=2        // why ? because again a=b and b did not change 
  thus output 1 2 2

简单的解决方案是 -

1.初始化product至1 // int product =1;

2.print product代替printf("%d\n",a); // printf("%d\n",product);

C“for”循环问题

2 个答案: