C/C++ 移动追加内容到文件尾部。

1、通过C语言文件函数库

1.1、通过追加到尾部字符命令

FILE* f = fopen(file_path.data(), "ab+");

1.2、不通过追加到尾部字符命令

FILE* f = fopen(path, "rb");

if (NULL != f) 
{

fseek(f, 0, SEEK_END);
}

Unix 平台（Linux/Android/MacOS X）

2、通过 Lseek 函数

int fd = open(file_path.data(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);

if (fd != -1)

{

  Lseek2(fd, 0, SEEK_END);

}

Impl 

bool Lseek2(int fd, int64_t offset, int whence) noexcept { return Lseek(fd, offset, whence) != -1; }

        int64_t Lseek(int fd, int64_t offset, int whence) noexcept {
            if (fd == -1) {
                return -1;
            }

            whence = std::max<int>(whence, SEEK_SET);

#if defined(__USE_GNU)
#if defined(SEEK_HOLE)
            whence = std::min<int>(whence, SEEK_HOLE);
#elif defined(SEEK_DATA)
            whence = std::min<int>(whence, SEEK_DATA);
#else
            whence = std::min<int>(whence, SEEK_END);
#endif
#else
            whence = std::min<int>(whence, SEEK_END);
#endif

#if defined(_MACOS)
            // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/lseek.2.html
            return lseek(fd, offset, whence);
#else
#if defined(_LARGEFILE64_SOURCE)
            // https://android.googlesource.com/platform/bionic/+/b23f193/libc/unistd/lseek64.c
            int64_t r = lseek64(fd, offset, whence);
            if (r != -1) {
                return r;
            }
#endif
            return lseek(fd, offset, whence);
#endif
        }