Question

C语言 循环语句例题 统计从键盘输入一行字符的个数

#include <stdio.h>
int main()
{
int n=0;
printf("input a string:\n");
while(getchar()!='\n');
{
n++;
}
printf("%d\n", n);
return 0;
}
为什么我输入多少个字符，他都只显示1?

Answer 1

Because there exits a redundant ";" bebind the satance of "while(getchar()!='\n')",so,when the programe running at this instruction,it will poform this while until you press "\n" ,then the next instruction "n++" will be performed,and it will be "1",thus,whatever you pressed,the result is "1".

Understand?
This is a low-grade problem,I wish you counld not make this mistake again.

Answer 2

#include "stdio.h"
void main()
{
 char c[100];
 int i;
 scanf("%s",c);
 i=printf("%s",c);
 printf("\n %d chars\n",i);
}

Answer 3

1、while(getchar()!='\n')后面多了一个分号，即多了一个空语句，所以后面的{ n++；}并不是while循环内的语句，只被执行了一次，所以n=1。
2、即使while后面没有多分号，最后结果也是1。这是因为getchar（）函数只能从键盘接收一个字符，它不能按照你的期望接收一个字符串，所以程序应改为：
#include <stdio.h>
int main()
{
int i=0,n=0;
char *s;
printf("input a string:\n");
gets(s);
while(s[i]!='\n');
{
n++;
i++;
}
printf("%d\n", n);
return 0;
}

Answer 4

whle那行多了个分好