
#define CATCH_CONFIG_MAIN
#include <catch2/catch.hpp>

int _testmain();


void safe_concat(char *dest, const char *src, int dest_size);

TEST_CASE("Appends all of src to dest if enough space", "[safe_concat]") {
    char buffer[20] = "Hello, ";
    safe_concat(buffer, "world!", 20);
    REQUIRE(std::string(buffer) == "Hello, world!");
}

TEST_CASE("Appends only as many characters from src as will fit", "[safe_concat]") {
    char buffer[10] = "Hi";
    safe_concat(buffer, " there!", 10);
    REQUIRE(std::string(buffer) == "Hi there!");

    char buffer2[8] = "Hi";
    safe_concat(buffer2, " there!", 8);
    // "Hi" (2) + " there" (6) = 8, but last is null-terminator, so only 5 from src
    REQUIRE(std::string(buffer2) == "Hi ther");
}

TEST_CASE("Ensures null-termination always", "[safe_concat]") {
    char buffer[5] = "1234";
    safe_concat(buffer, "56789", 5);
    REQUIRE(buffer[4] == '\0');
    REQUIRE(std::string(buffer) == "1234");

    char buffer2[6] = "";
    safe_concat(buffer2, "ABCDE", 6);
    REQUIRE(buffer2[5] == '\0');
    REQUIRE(std::string(buffer2) == "ABCDE");
}

TEST_CASE("Does not write past dest_size boundary", "[safe_concat]") {
    char buffer[5] = "abc";
    // Fill the rest with known value
    buffer[4] = 'X';
    safe_concat(buffer, "de", 5);
    REQUIRE(buffer[4] == '\0');
    REQUIRE(std::string(buffer) == "abcd");
}

TEST_CASE("Handles empty src and/or empty dest correctly", "[safe_concat]") {
    char buffer[10] = "";
    safe_concat(buffer, "abc", 10);
    REQUIRE(std::string(buffer) == "abc");

    char buffer2[10] = "hello";
    safe_concat(buffer2, "", 10);
    REQUIRE(std::string(buffer2) == "hello");

    char buffer3[1] = "";
    safe_concat(buffer3, "abc", 1);
    REQUIRE(std::string(buffer3) == "");
}

test.cpp

Learn how strings are represented and manipulated in the C programming language. Understand the unique characteristics of C strings, including memory management, null-termination, and common string operations.

Explore how strings are represented as arrays of characters in C, the role of null-termination, and the implications for memory management.

Learn how to initialize strings, read input from the user, and output strings in C.

Explore the most frequently used string operations in C, including copying, comparison, concatenation, and length calculation.

Challenge: Concatenating Strings

Solution