C/C++ Basics

Data Types and Formatted Output

C and C++ share fundamental numeric types, but their preferred formatting mechanisms differ.

What is Data Types and Formatted Output?

C and C++ share fundamental numeric types, but their preferred formatting mechanisms differ.

Declare integer and floating-point values and print them safely.

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>

int main(void) {
    int items = 7;
    double price = 3.5;
    printf("items=%d total=%.2f\n", items, items * price);
    return 0;
}

Expected output

items=7 total=24.50

C++

Run code →

main.cpp

#include <iomanip>
#include <iostream>

int main() {
    int items = 7;
    double price = 3.5;
    std::cout << "items=" << items << " total="
              << std::fixed << std::setprecision(2) << items * price << '\n';
}

Expected output

items=7 total=24.50

C and C++ comparison

printf requires a format specifier that matches each promoted argument. C++ stream insertion selects an overload from the value type and iomanip controls precision.

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.