Constants in C Language:

Constants in C

Constants are fixed values that do not change during the execution of a program. C supports several types of constants, including integer constants, floating-point constants, character constants, string constants, enumeration constants, and symbolic constants.

Integer Constants

Integer constants are whole numbers without a fractional part. They can be specified in decimal, octal, or hexadecimal form:

Type	Example	Description
Decimal	`42`	Base 10 (e.g., `42`)
Octal	`052`	Base 8 (e.g., `052` represents decimal `42`)
Hexadecimal	`0x2A`	Base 16 (e.g., `0x2A` represents decimal `42`)

Floating-Point Constants

Floating-point constants represent real numbers and include a decimal point or an exponent. Examples:

Type	Example	Description
Decimal	`3.14`	Standard decimal notation
Exponential	`2.5e3`	Represents `2.5 × 10³` (i.e., `2500`)

Character Constants

Character constants represent single characters enclosed in single quotes. Examples:

'A' '9' '$'

String Constants

String constants are sequences of characters enclosed in double quotes. Examples:

"Hello, World!" "12345" "Special characters: @$#&*"

Enumeration Constants

Enumeration constants are a set of named integer constants. They are defined using the enum keyword. For example:

enum color {RED, GREEN, BLUE}; enum color myColor = RED;

In this example, RED, GREEN, and BLUE are enumeration constants that correspond to the values 0, 1, and 2 respectively.

Symbolic Constants

Symbolic constants are defined using the #define preprocessor directive. They are used to give a name to a constant value. For example:

#define PI 3.14159 #define MAX_LENGTH 100

In this example, PI and MAX_LENGTH are symbolic constants.

Examples

Here are some examples of how these constants can be used in a C program:

#include <stdio.h> #define PI 3.14159 #define MAX_LENGTH 100 enum color {RED, GREEN, BLUE}; int main() { // Integer constants int dec = 42; int oct = 052; int hex = 0x2A; // Floating-point constants float f = 3.14; double exp = 2.5e3; // Character constants char c = 'A'; // String constants char str[] = "Hello, World!"; // Enumeration constants enum color myColor = RED; printf("Decimal: %d\n", dec); printf("Octal: %d\n", oct); printf("Hexadecimal: %d\n", hex); printf("Float: %f\n", f); printf("Exponential: %e\n", exp); printf("Character: %c\n", c); printf("String: %s\n", str); printf("Enumeration constant (color): %d\n", myColor); printf("Symbolic constant PI: %f\n", PI); printf("Symbolic constant MAX_LENGTH: %d\n", MAX_LENGTH); return 0; }