Handle a failed string-to-integer conversion.
C++: stoi throws invalid_argument when no conversion can be performed.
#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;
try { std::cout << std::stoi("invalid") << "\n"; }
catch (const std::invalid_argument&) { std::cout << "Invalid integer\n"; }
}
Expected output EXAMPLE
Invalid integer
Details
Save as snippet.cpp; compile with g++ -std=c++17 -Wall -Wextra snippet.cpp -pthread -o snippet, then run ./snippet. stoi throws invalid_argument when no conversion can be performed.
Out-of-range values throw out_of_range. Check the consumed position when trailing text must also be rejected.
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
3774e90307e2b33f894c94c83a7181678dad33db0f870f98c446f8b7ca236d0d- 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
Invalid integer
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.