Variables & Primitive Types

🔵 C Programming Lesson 2 Beginner

C is a statically-typed language. Every variable must have an declared data type specifying the exact layout size of memory to allocate for it on stack registers.

1 Core Primitive Types & Specifiers

The standard primitives in C are basic numerical blocks:

Type	Typical Size	Format Specifier	Description
char	1 byte	`%c`	Single ASCII character
int	4 bytes	`%d` or `%i`	Integer numerical values
float	4 bytes	`%f`	Single-precision floating points
double	8 bytes	`%lf`	Double-precision floating points (default decimal representation)

Qualifiers: You can modify ranges using qualifiers like `short`, `long`, `long long`, or `unsigned` (which handles positive values only, doubling the positive range capacity):

`unsigned int score = 5000;` (Does not store negative values)
`long long bankBalance = 99999999999LL;` (Utilizes format specifier `%lld`)

2 Declaration, Initialization, & Specifiers

Let's run a program declaring different C types and printing them out with their matching formatting parameters:

C — Data Types & Specifiers ▶ Run Code

#include <stdio.h>

int main() {
    char grade = 'A';
    int score = 95;
    float temp = 98.6f;
    double pi = 3.1415926535;
    unsigned int id = 452291;

    // Formatting output using placeholder parameters
    printf("Grade: %c\n", grade);
    printf("Score: %d\n", score);
    
    // Controlling decimal precision formatting
    printf("Temperature (default): %f\n", temp);
    printf("Temperature (2 decimals): %.2f\n", temp);
    printf("Pi (8 decimals): %.8lf\n", pi);
    printf("Unsigned ID: %u\n", id);

    return 0;
}

3 Code Challenge

Challenge: Write a program that calculates the area of a circle with a radius of `5.5`. Define radius and area as `double` variables, use `3.14159` as pi, compute the area, and print the output formatted to exactly 4 decimal places.