std::ferror(3)

🦋 std::ferror(3) 🦋 — C++ Standard Libary

okay so bestie, we are in the C++ Standard Libary and this is the page for std::ferror(3). The header is giving “tiny but iconic,” and the manual name is literally C++ Standard Libary. Yes, that spelling is what the header says, not me, ily. 💅

🎀 NAME 🎀

std::ferror - std::ferror

literally the name, no cap. The page is std::ferror(3), and the NAME section is just the same thing twice like a mirror selfie. 🪞✨

📚 Synopsis 📚

Defined in header <cstdio>

int ferror( std::FILE* stream );

This bad boy checks the given stream for errors. You hand it a stream, it tells you if that stream has error energy. 🫶

💖 Parameters 💖

• stream — the file stream to check. That’s the thing you’re side-eyeing for errors, bestie.

🌸 Return value 🌸

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

So: nonzero means errors happened on that file stream; 0 means no errors found. Simple, clean, iconic. ✨

🧚 Example 🧚

Run this code, fr fr:

// 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");
}

the stray sequence line is in the original snippet too, bestie — don’t come for me 😭💀

🌈 Output 🌈

Error indicator set

👑 See also 👑

• clearerr — clears errors. It’s a function.
• feof — checks for the end-of-file. It’s a function.
• fail — checks if an error has occurred. It’s a public member function of std::basic_ios<CharT,Traits>.
• C documentation for ferror — yes, the C version of this whole situation.

okay that’s the whole manual page, mwah 💋 — source: cppreference.com, version/date: 2024.06.10, page: std::ferror(3). 🫶🎀