C Programming - C Literals

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C Programming - C Literals

C Literals

In C, literals are fixed values directly embedded in the code. They represent constant values used in a program and cannot be changed during execution. Literals are categorized based on their type, such as integer, floating-point, character, string, etc.

Types of Literals in C

1. Integer Literals

• Represent whole numbers without a fractional part.
• Can be written in decimal, octal, or hexadecimal notation.

Examples:

int decimal = 10;     // Decimal literal
int octal = 012;      // Octal literal (starts with 0)
int hexadecimal = 0xA; // Hexadecimal literal (starts with 0x or 0X)

2. Floating-Point Literals

• Represent numbers with a fractional part.
• Can be written in decimal or scientific/exponential notation.

Examples:

float decimal = 3.14;         // Decimal literal
float scientific = 3.14e2;    // Scientific notation (equivalent to 3.14 × 10^2)
float negative = -0.001;      // Negative floating-point literal

3. Character Literals

• Represent single characters enclosed in single quotes (').
• Each character literal corresponds to an ASCII value.

Examples:

char letter = 'A';       // Character literal
char number = '5';       // Character literal (not numeric)
char newline = '\n';     // Escape sequence

4. String Literals

• Represent a sequence of characters enclosed in double quotes (").
• Always end with a null character (\0).

Examples:

char str[] = "Hello, World!";   // String literal

5. Boolean Literals

• Introduced with <stdbool.h> in C99.
• Represent true or false values.

Examples:

#include <stdbool.h>
bool isValid = true;   // Boolean literal

6. Constant Literals

• Represent constant values using the const keyword.

Examples:

const int MAX = 100;   // Constant integer literal

Escape Sequences in Character and String Literals

Escape sequences are special character literals that represent non-printable or control characters.

Rules for Literals

1. Integer Literals:
• No decimal point is allowed.
• Must fit within the range of the data type (e.g., int, long).
2. Floating-Point Literals:
• Must include a decimal point or use scientific notation.
3. Character Literals:
• Enclosed in single quotes and represent one character only.
4. String Literals:
• Enclosed in double quotes and represent multiple characters.

Examples of Different Literals in a Program

#include <stdio.h>
#include <stdbool.h>
 
int main() {
    int decimal = 42;           // Integer literal
    float pi = 3.14159;         // Floating-point literal
    char letter = 'C';          // Character literal
    char newline = '\n';        // Escape sequence
    const char *message = "Hello, World!"; // String literal
    bool isActive = true;       // Boolean literal
 
    printf("Integer: %d\n", decimal);
    printf("Float: %.2f\n", pi);
    printf("Character: %c\n", letter);
    printf("String: %s\n", message);
    printf("Boolean: %d\n", isActive);  // Output: 1 (true)
 
    return 0;
}

Key Points

1. Literals represent fixed values in code and are immutable.
2. Different types of literals exist to match the data types used in C programs.
3. Escape sequences are used to represent non-printable characters.
4. Use const for literals you don't want to change.

Literals are fundamental in C, forming the building blocks for initializing and manipulating data.