C/C++ Basics

Arrays and Strings

C strings are null-terminated character arrays; C++ std::string owns its storage and tracks its length.

What is Arrays and Strings?

C strings are null-terminated character arrays; C++ std::string owns its storage and tracks its length.

Traverse fixed arrays and safely measure text.

Important points

Compile with warnings enabled and fix every warning.
Know the lifetime and type of every value.
Validate input and keep array bounds explicit.

C and C++ code examples

Run code →

main.c

#include <stdio.h>
#include <string.h>

int main(void) {
    int values[] = {3, 5, 8, 13};
    char name[] = "Ada";
    size_t count = sizeof values / sizeof values[0];
    printf("%s: %zu values, %zu letters\n", name, count, strlen(name));
    return 0;
}

Expected output

Ada: 4 values, 3 letters

C++

Run code →

main.cpp

#include <array>
#include <iostream>
#include <string>

int main() {
    std::array values{3, 5, 8, 13};
    std::string name = "Ada";
    std::cout << name << ": " << values.size()
              << " values, " << name.size() << " letters\n";
}

Expected output

Ada: 4 values, 3 letters

C and C++ comparison

sizeof can determine a local array's element count but not an array received as a pointer parameter. strlen scans for the null terminator; std::string::size is constant time.

C exposes small procedural APIs and makes representation details explicit.

C++

C++ retains the low-level model while adding safer library types and abstractions.

Practice exercises

Run both versions, then modify them to observe the different language guarantees.

Add invalid and boundary-value inputs.
Compile with -Wall -Wextra -Wpedantic.
Move reusable declarations into a header and implementation file.