Replace text using captured regex groups.
C++: Numbered replacement groups can rearrange a known two-part name.
#include <iostream>
#include <string>
#include <string_view>
#include <vector>
#include <array>
#include <algorithm>
#include <numeric>
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <stack>
#include <deque>
#include <tuple>
#include <bitset>
#include <memory>
#include <optional>
#include <variant>
#include <functional>
#include <charconv>
#include <regex>
#include <fstream>
#include <sstream>
#include <filesystem>
#include <iomanip>
#include <cmath>
#include <cctype>
#include <limits>
#include <chrono>
#include <thread>
#include <future>
#include <mutex>
#include <atomic>
#include <condition_variable>
int main() {
std::cout << std::boolalpha;
std::cout << std::regex_replace(std::string("Ada Lovelace"),std::regex("([^ ]+) (.+)"),"$2, $1") << "\n";
}
Expected output EXAMPLE
Lovelace, Ada
Details
Save as snippet.cpp; compile with g++ -std=c++17 -Wall -Wextra snippet.cpp -pthread -o snippet, then run ./snippet. Numbered replacement groups can rearrange a known two-part name.
Tested on Ubuntu 24.04.5 LTS · · g++ (Ubuntu 13.3.0-6ubuntu2~24.04.1) 13.3.0 · g++ 4:13.2.0-7ubuntu1
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
g++ -std=c++17 -Wall -Wextra -Werror snippet.cpp -pthread -lm -o snippet && ./snippet- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
96c7e5e742cafb0f36d71e67d288d630591c52ec2a6fe428b05eb831243573c1- Dependencies
- g++ 4:13.2.0-7ubuntu1
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
Lovelace, Ada
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.