计算 C 文件中未知数量的字符

Question

我正在寻找一种使用 C 语言计算文件中未知字符数的简单方法。谢谢你的帮助

Answer 1

POSIX 方式(可能是您想要的方式):

off_t get_file_length( FILE *file ) {
    fpos_t position; // fpos_t may be a struct and store multibyte info
    off_t length; // off_t is integral type, perhaps long long

    fgetpos( file, &position ); // save previous position in file

    fseeko( file, 0, SEEK_END ); // seek to end
    length = ftello( file ); // determine offset of end

    fsetpos( file, &position ); // restore position

    return length;
}

标准的C方式(迂腐):

long get_file_length( FILE *file ) {
    fpos_t position; // fpos_t may be a struct and store multibyte info
    long length; // break support for large files on 32-bit systems

    fgetpos( file, &position ); // save previous position in file

    if ( fseek( file, 0, SEEK_END ) // seek to end
        || ( length = ftell( file ) ) == -1 ) { // determine offset of end
        perror( "Finding file length" ); // handle overflow
    }

    fsetpos( file, &position ); // restore position

    return length;
}

如果你想知道多字节字符的数量，你需要用例如fgetwc读取整个文件。