检查文件是否存在于 c 中的最佳方法是什么？ (跨平台)

Question

Is there a better way than simply trying to open the file?

int exists(const char *fname)
{
    FILE *file;
    if ((file = fopen(fname, "r")))
    {
        fclose(file);
        return 1;
    }
    return 0;
}

转载于:https://stackoverflow.com/questions/230062/whats-the-best-way-to-check-if-a-file-exists-in-c-cross-platform

Answer 1

Look up the access() function, found in unistd.h. You can replace your function with

if( access( fname, F_OK ) != -1 ) {
    // file exists
} else {
    // file doesn't exist
}

You can also use R_OK, W_OK, and X_OK in place of F_OK to check for read permission, write permission, and execute permission (respectively) rather than existence, and you can OR any of them together (i.e. check for both read and write permission using R_OK|W_OK)

Update: Note that on Windows, you can't use W_OK to reliably test for write permission, since the access function does not take DACLs into account. access( fname, W_OK ) may return 0 (success) because the file does not have the read-only attribute set, but you still may not have permission to write to the file.