Skip to main content

Overview of C

INTRODUCTION TO C LANGUAGE

C is a general-purpose programming language that is closely related to how computer machines work. Although often considered difficult to learn, C is actually a simple language with vast capabilities.

Here are some key points to note in C:

  • Case-sensitive: C distinguishes between uppercase and lowercase letters. For example, printf and Printf are two different things.
  • Space-insensitive: Separators such as spaces, tabs, or new lines do not affect the program.
  • Semicolon: Every statement must end with a semicolon (;).
  • Multiple Statements: Several statements can be written on the same line.

SIMPLE C PROGRAM: PRINTING A LINE OF TEXT

The simplest C program is a program that prints text. Here is an example:

#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

Output:

Hello, World!

Parts of the Program

  1. Comment:

    • Single-line comments use //, while multi-line comments use /* ... */.
    // This is a single-line comment
/* 
   This is a 
   multi-line comment
*/

  2. Header File:

    • Header files like stdio.h are required to use functions such as printf() or scanf().
    #include <stdio.h>

  3. Main Function:

    • The main() function is the program’s entry point.
    • int main() indicates that the function returns an integer (0 for success, 1 or more for failure).
    int main() {
    // Program code
    return 0; // Indicates successful program execution
}

  4. The printf() Function:

    • This function is used to print output to the screen.
    • \n is an escape sequence meaning newline (new row).
    printf("Hello, World!\n");

VARIABLES AND DATA TYPES

Variables are "containers" for storing values. The data type determines the kind of value that can be stored in a variable.

Types of Data in C

  1. int - For integer values.

    int number1;  // Variable without initialization (random value)
int number2 = 20;  // Variable initialized with value 20

  2. float - For decimal values.

    float decimal = 3.14;

  3. char - For storing a single character.

    char letter = 'A';

Here is a complete diagram of data types in C:
Alt text

Naming Variables

  • Variable names must start with a letter or an underscore (_).
  • Spaces or punctuation marks (such as ?, !, etc.) are not allowed.
  • Case-sensitive: name and Name are different variables.

Example:

int age = 20;      // Valid
float height = 170; // Valid
char initial = 'A'; // Valid
int ageOfFather = 45; // Valid

int 2age = 20;     // Invalid (cannot start with a number)

Complete Example

Here is an example program using variables and data types:

#include <stdio.h>

int main() {
    int age = 25;
    float height = 170.5;
    char initial = 'A';

    printf("Age: %d years\n", age);
    printf("Height: %.2f cm\n", height);
    printf("Initial: %c\n", initial);

    return 0;
}

Output:

Age: 25 years
Height: 170.50 cm
Initial: A
Back to top