C++

C++ is a systems imperative and object-oriented language first appearing in 1985.

Hello World

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <memory>
#include <fstream>
#include <cmath>
#include <chrono>
#include <thread>

// BEGIN_FRAGLET
int main() {
    std::cout << "Hello World!" << std::endl;
    return 0;
}
// END_FRAGLET

Coding Guide

Language Version

C++ (G++ compiler, musl libc)

Execution Model

• Compiled language using G++
• Code is compiled to a binary, then executed
• Standard C++ execution model with main() function

Key Characteristics

• Statically typed
• Case-sensitive
• Object-oriented (classes, inheritance, polymorphism)
• Supports templates (generic programming)
• Rich standard library (STL)
• Requires explicit compilation step
• Uses musl libc (Alpine's C library)

Fragment Authoring

Write valid C++ code. Your fragment can define classes, functions, and the main() function. Standard library includes are already in place. Your fragment will be compiled and executed.

Available Headers

The template includes these standard headers:

• <iostream> - Input/output streams (cout, cin, cerr)
• <vector> - Dynamic arrays
• <string> - String class
• <algorithm> - Algorithms (sort, find, transform)
• <map>, <unordered_map> - Associative containers
• <set>, <unordered_set> - Set containers
• <memory> - Smart pointers (unique_ptr, shared_ptr)
• <fstream> - File I/O
• <cmath> - Mathematical functions
• <chrono> - Time utilities
• <thread> - Threading support

Common Patterns

• Print: std::cout << "message" << std::endl;
• Variables: int x = 10; or auto x = 10;
• Classes: class MyClass { ... };
• Functions: int add(int a, int b) { return a + b; }
• Templates: template<typename T> T max(T a, T b) { ... }
• Vectors: std::vector<int> vec = {1, 2, 3};
• Strings: std::string s = "Hello";
• Smart pointers: auto ptr = std::make_unique<int>(42);
• Loops: for (int i = 0; i < 10; i++) { ... } or for (auto& item : vec) { ... }

Examples

// Simple output
int main() {
    std::cout << "Hello from fragment!" << std::endl;
    return 0;
}

// Variables and calculations
int main() {
    int a = 5;
    int b = 10;
    std::cout << "Sum: " << (a + b) << std::endl;
    return 0;
}

// Using STL vector
int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    int sum = 0;
    for (int num : numbers) {
        sum += num;
    }
    std::cout << "Vector sum: " << sum << std::endl;
    return 0;
}

// String operations
int main() {
    std::string message = "Hello";
    message += " World!";
    std::cout << message << std::endl;
    return 0;
}

// Simple class
class Calculator {
public:
    int add(int a, int b) {
        return a + b;
    }
};

int main() {
    Calculator calc;
    std::cout << "5 + 3 = " << calc.add(5, 3) << std::endl;
    return 0;
}

// Template function
template<typename T>
T maximum(T a, T b) {
    return (a > b) ? a : b;
}

int main() {
    std::cout << "Max(5, 10) = " << maximum(5, 10) << std::endl;
    std::cout << "Max(3.14, 2.71) = " << maximum(3.14, 2.71) << std::endl;
    return 0;
}

Caveats

• Fragments must be valid C++ code that compiles
• Remember to include std::endl or "\n" for newlines
• Variables, classes, and functions are scoped to the file
• The code is compiled fresh each time, so compilation errors will fail execution
• musl libc may have some differences from glibc in edge cases
• Use std:: prefix for standard library components, or add using namespace std; at the top of your fragment

Fraglet Scripts

Echo Args

#!/usr/bin/env -S fragletc --vein=cpp
#include <iostream>
int main(int argc, char *argv[]) {
    if (argc > 1) std::cout << "First: " << argv[1] << std::endl;
    if (argc > 2) std::cout << "Second: " << argv[2] << std::endl;
    return 0;
}

Stdin Upper

#!/usr/bin/env -S fragletc --vein=cpp
#include <iostream>
#include <cctype>
int main() {
    char c;
    while (std::cin.get(c)) std::cout << static_cast<char>(std::toupper(static_cast<unsigned char>(c)));
    return 0;
}

Test

#!/usr/bin/env -S fragletc --vein=cpp
int main() {
    std::cout << "Hello World!" << std::endl;
    return 0;
}

Connections

Container Info