std::ferror

 

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FILE fpos_t	stdinstdoutstderr
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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 <clocale>
#include <cstdio>
#include <cstdlib>
#include <cwchar>
 
int main()
{
    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>)
C documentation for ferror