Counting the number of files in a directory is a common task that can be accomplished by iterating through the directory entries and incrementing a counter for each file.
Here’s an example that counts regular files in a directory:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
int main() {
fs::directory_iterator start{R"(c:\test)"};
fs::directory_iterator end{};
int file_count = 0; // Initialize counter
for (auto iter{start}; iter != end; ++iter) {
if (iter->is_regular_file()) {
++file_count;
}
}
std::cout << "Number of files: " << file_count;
}Number of files: 3Steps to Count Files:
- Initialize Iterator: Create a
std::filesystem::directory_iteratorfor the target directory. - Initialize Counter: Set a counter variable to zero.
- Iterate and Count: Loop through the directory entries, incrementing the counter for each regular file.
Counting Files and Directories Separately:
You can also count files and directories separately:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
int main() {
fs::directory_iterator start{R"(c:\test)"};
fs::directory_iterator end{};
int file_count = 0;
int dir_count = 0;
for (auto iter{start}; iter != end; ++iter) {
if (iter->is_regular_file()) {
++file_count;
} else if (iter->is_directory()) {
++dir_count;
}
}
std::cout << "Number of files: "
<< file_count << '\n';
std::cout << "Number of directories: "
<< dir_count << '\n';
}Number of files: 3
Number of directories: 1Using Range-Based Algorithms:
You can also use range-based algorithms to count files:
#include <filesystem>
#include <iostream>
#include <ranges>
namespace fs = std::filesystem;
int main() {
auto entries = std::ranges::subrange{
fs::directory_iterator{R"(c:\test)"},
fs::directory_iterator{}
};
auto file_count = std::ranges::count_if(
entries,
[](const fs::directory_entry& entry) {
return entry.is_regular_file();
}
);
std::cout << "Number of files: " << file_count;
}Number of files: 3Counting with Recursive Iteration:
If you want to count files in a directory and its subdirectories, use std::filesystem::recursive_directory_iterator:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
int main() {
fs::recursive_directory_iterator start{
R"(c:\test)"};
fs::recursive_directory_iterator end{};
int file_count = 0;
for (auto iter{start}; iter != end; ++iter) {
if (iter->is_regular_file()) {
++file_count;
}
}
std::cout << "Number of files: " << file_count;
}Number of files: 3Counting files is a fundamental operation that can be easily implemented using the techniques shown above, whether for flat or recursive directory structures.
Answers to questions are automatically generated and may not have been reviewed.
Directory Iterators
An introduction to iterating through the file system, using directory iterators and recursive directory iterators
