在 C 中的 fgets() 之后清除输入缓冲区

Question

#include <stdio.h>
int main()
{
  char name[10];
  for(int i=0;i<=10;i++)
  {
    printf("Who are you? ");
    if(fgets(name,10,stdin)!=NULL)
    printf("Glad to meet you, %s.\n",name);
  }
  return(0);
}

当我输入超过 10 个字符时，循环会跳过。

Who are you? aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
Glad to meet you, aaaaaaaaa.
Who are you? Glad to meet you, aaaaaaaaa.
Who are you? Glad to meet you, aaaaaaaaa.
Who are you? Glad to meet you, aaaaaaaaa.
Who are you? Glad to meet you, aaaaaaaaa.
Who are you? Glad to meet you, aaaaaaaaa.
Who are you? Glad to meet you, aaaaaaa

我想我想清除输入缓冲区中剩余的字符。最好的方法是什么...？

Answer 1

来自 fgets 的文档（强调我的）：

Reads characters from stream and stores them as a C string into str until (num-1) characters have been read or either a newline or the end-of-file is reached, whichever happens first.

因此您的输入（超出缓冲区）以 9 个字符（+1 个空终止字符）的块形式读取。

您需要重复调用fgets，直到最后读取的字符是换行符(\n)。

Answer 2

检查 name.

中是否存在换行符

#include <stdio.h>
#include <string.h>

int main(void){
    char name[10];

    for(int i=0;i<=10;i++){
        printf("Who are you? ");
        if(fgets(name,10,stdin)){
            char *p;
            if(p=strchr(name, '\n')){//check exist newline
                *p = 0;
            } else {
                scanf("%*[^\n]");scanf("%*c");//clear upto newline
            }
            printf("Glad to meet you, %s.\n", name);
        }
    }
    return(0);//Parentheses is not necessary
}

Answer 3

您需要使用类似下面的内容来查找 \n：

/* flush unread input buffer */
while( ! strchr( name, '\n' ) )
    if( ! fgets(name,(sizeof name),stdin) )
        break;

注意：不确定您认为这是错误还是功能，但短名称将包括最后的 \n。结果如下：

Glad to meet you SSS
.

Answer 4

检查 fgets() 是否获得了 '\n'。如果没有'\n'，则表示当前行中的某些字符还没有被读取。你可以直接忽略它们。

    printf("Who are you? ");
    if (fgets(name, 10, stdin) != NULL) {
        if (!strchr(name, '\n')) {
            // consume rest of chars up to '\n'
            int ch;
            while (((ch = getchar()) != EOF) && (ch != '\n')) /* void */;
            if (ch == EOF) /* input error */;
            printf("Glad to meet you, %s.\n", name);
        } else {
            printf("Glad to meet you, %s.", name); // name includes ENTER
        }
    }

在 C 中的 fgets() 之后清除输入缓冲区

Clear input buffer after fgets() in C

c

inputstream

fgets

fflush