#include <stdio.h>
int main (void)
{
  int n, number, summary = 0, counter;
  for (counter = 1; counter <= 5; counter++)
{
    printf ("what number do you want? ");
    scanf ("%i", &number);
    for (n = 1; n <= number; n++)
        summary += n;
      printf ("The number %i is %i\n\n", number, summary);
      getch();
}
      return 0;
}
为什么上面的运行结果是错的 把summary = 0这个给变量赋值这个语句写到scanf函数下面的一行结果就没错误啊？

int n, number, summary, counter;


scanf ("%i", &number);
 summary = 0；     
for (n = 1; n <= number; n++)
改成这样就没问题 请问为什么？

scanf ("%i", &number);
summary = 0；     
即每次输入number时先把summary清0，比如你输入的number=5，执行语句 for (n = 1; n <= number; n++)
        summary += n;
后summary=15，下次循环时比如你输入3，执行语
句for (n = 1; n <= number; n++)
        summary += n;
后结果就是1+2+3+15=21了而不是1+2+3=6

也就是说如果你把summary = 0放上面程序只是定义时赋值为0，以后值会累加在变量summary里面

哦 谢谢了