# std::ferror

From cppreference.com
< cpp‎ | io‎ | c

Defined in header `<cstdio>` |  |
int ferror( std::FILE * stream ); |  |

Checks the given stream for errors.

### Parameters

stream | - | the file stream to check

### Return value

Nonzero value if the file stream has errors occurred, ​0​ otherwise

### Example

Run this code

    #include <cstdio>
    #include <cstdlib>
    #include <clocale>
    #include <cwchar>

    int main(void)
    {
        const char *fname = std::tmpnam(nullptr);
        std::FILE* f = std::fopen(fname, "wb");
        std::fputs("\xff\xff\n", f); // not a valid UTF-8 character sequence
        std::fclose(f);

        std::setlocale(LC_ALL, "en_US.utf8");
        f = std::fopen(fname, "rb");
        std::wint_t ch;
        while ((ch=std::fgetwc(f)) != WEOF) // attempt to read as UTF-8
              std::printf("%#x ", ch);

        if (std::feof(f))
            puts("EOF indicator set");
        if (std::ferror(f))
            puts("Error indicator set");
    }

Output:

    Error indicator set

### See also

clearerr | clears errors (function)
feof | checks for the end-of-file (function)
fail | checks if an error has occurred (public member function of `std::basic_ios<CharT,Traits>`)

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