How do i check if a file is a regular file in C++?

问题:

How do i check in C++ if a file is a regular file (and is not a directory, a pipe, etc.)? I need a function isFile().

DIR *dp;
struct dirent *dirp;

while ((dirp = readdir(dp)) != NULL) {
if ( isFile(dirp)) {
     cout << "IS A FILE!" << endl;
i++;
}

I've tried comparing dirp->d_type with (unsigned char)0x8, but it seems not portable through differents systems.

回答1:

You need to call stat(2) on the file, and then use the S_ISREG macro on st_mode.

回答2:

You can use the portable boost::filesystem (The standard C++ library could not have done this up until recent introduction of std::filesystem in C++17):

#include <boost/filesystem/path.hpp>
#include <boost/filesystem/operations.hpp>
#include <iostream>

int main() {
    using namespace boost::filesystem;

    path p("/bin/bash");
    if(is_regular_file(p)) {
        std::cout << "exists and is regular file" << std::endl;
    }
}

回答3:

C++ itself doesn't deal with file systems, so there's no portable way in the language itself. Platform-specific examples are stat for *nix (as already noted by Martin v. Löwis) and GetFileAttributes for Windows.

Also, if you're not allergic to Boost, there's fairly cross-platform boost::filesystem.

回答4:

In C++17, you may use std::filesystem::is_regular_file

#include <filesystem> // additional include

if(std::filesystem::is_regular_file(yourFilePathToCheck)) 
    ; //Do what you need to do

Note that earlier version of C++ may have had it under std::experimental::filesystem (Source: http://en.cppreference.com/w/cpp/filesystem/is_regular_file)

回答5:

Thank you all for the help, i've tried with

while ((dirp = readdir(dp)) != NULL) { 
   if (!S_ISDIR(dirp->d_type)) { 
        ... 
        i++; 
   } 
} 

And it works fine. =)

回答6:

#include <boost/filesystem.hpp>

bool isFile(std::string filepath)
{
    boost::filesystem::path p(filepath);
    if(boost::filesystem::is_regular_file(p)) {
        return true;
    }
    std::cout<<filepath<<" file does not exist and is not a regular file"<<std::endl;
    return false;
}