"ferror" 测试 "scanf" 输入

Question

我试图在下一个程序中输入错误数据，但无法识别错误。一次我输入数字数据，下一次输入字符串数据，但程序没有反应：

#include <iostream>
#include <cstdio>
#include <cstdlib>

using namespace std;

int main(void)
{
    int i;

    scanf("%d",&i);

    if(ferror(stdin))
        printf("Error is ocurred!");
}

Answer 1

不要假设函数的作用。阅读它的文档。

https://www.cplusplus.com/reference/cstdio/ferror/

int ferror ( FILE * stream );

Check error indicator

Checks if the error indicator associated with stream is set, returning a value different from zero if it is.

This indicator is generally set by a previous operation on the stream that failed, and is cleared by a call to clearerr, rewind or freopen.

所以这取决于 scanf 是否设置了错误指示器，在这种情况下它没有设置。

改为使用：

if(scanf("%d",&i) != 1) {
    // Error code

哦，不要使用 use namespace std Why is "using namespace std;" considered bad practice?

"ferror" 测试 "scanf" 输入

"ferror" tests "scanf" input

c++

scanf

ferror