You can stop the iteration prematurely by using the break statement within your loop. This allows you to exit the loop based on a specific condition or requirement.
Here’s an example where we stop the iteration after finding a specific file:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
int main() {
fs::directory_iterator start{R"(c:\test)"};
fs::directory_iterator end{};
for (auto iter{start}; iter != end; ++iter) {
std::cout << iter->path().string() << '\n';
if (iter->path().filename() == "stop_here.txt") {
break; // Stop iteration
}
}
}c:\test\file1.txt
c:\test\file2.txt
c:\test\stop_here.txtCommon Use Cases for Stopping Early:
- Finding a Specific File or Directory: Stop once a specific entry is found.
- Resource Limits: Stop if a certain resource limit is reached (e.g., memory usage, number of processed files).
- User Input: Allow the user to interrupt the process based on input or an external event.
Example: Stopping Based on File Count:
Here’s another example where we stop after processing a certain number of files:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
int main() {
fs::directory_iterator start{R"(c:\test)"};
fs::directory_iterator end{};
int count = 0;
// Maximum files to process
const int max_files = 5;
for (auto iter{start}; iter != end; ++iter) {
if (count >= max_files) {
break; // Stop after processing max_files
}
std::cout << iter->path().string() << '\n';
++count;
}
}c:\test\file1.txt
c:\test\file2.txt
c:\test\file3.txt
c:\test\file4.txt
c:\test\file5.txtHandling Complex Conditions:
For more complex conditions, you can combine multiple checks:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
bool should_stop(const fs::directory_entry& entry) {
// Example condition: stop at specific file
// or if file size exceeds limit
return entry.path().filename() == "stop_here.txt"
|| entry.is_regular_file()
&& entry.file_size() > 1024;
}
int main() {
fs::directory_iterator start{R"(c:\test)"};
fs::directory_iterator end{};
for (auto iter{start}; iter != end; ++iter) {
if (should_stop(*iter)) {
break;
}
std::cout << iter->path().string() << '\n';
}
}c:\test\file1.txt
c:\test\file2.txt
c:\test\file3.txtStopping the iteration prematurely is a straightforward process in C++. Use conditions and the break statement to control the flow of your directory traversal as needed.
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Directory Iterators
An introduction to iterating through the file system, using directory iterators and recursive directory iterators
