typedef vs define in C

typedef

 typedef is used to create a new name (alias) for an existing data type.

 It doesn't define a new data type but creates a new name that can be used interchangeably with the existing data type, enhancing code readability.

Syntax of typdef:

typedef existing_data_type new_data_type;

Example:

// Program for typedef
#include<stdio.h> 

// Using typedef to create an alias for int
typedef int integer;

int main() {
    integer num1 = 5;
    integer num2 = 3;
    integer sum;

    // Adding two integer values
    sum = num1 + num2;

    printf("Sum of %d and %d is %d\n", num1, num2, sum);

    return 0;
}

Output:

Sum of 5 and 3 is 8

define

 #define is a preprocessor directive used to define constants or macros.

 It replaces all occurrences of identifier with value in the code during preprocessing.

 It doesn't require a data type and doesn't reserve memory space for the identifier.

Syntax of define:

#define identifier value

Example:

 // Program for define in C
#include<stdio.h> 

// Using #define to define a constant for PI
#define PI 3.14159

int main() {
    float radius = 5.0;
    float circle_area;

    // Calculating the area of a circle using the defined constant PI
    circle_area = PI * radius * radius;

    printf("Area of the circle and radius %.2f is %.2f\n", radius, circle_area);

    return 0;
}

Output:

Area of the circle and radius 5.00 is 78.54

Difference between typedef and #define

Feature	typedef	#define
Memory Allocation	Allocates memory for the new data type	Doesn't allocate memory; replaced during preprocessing.
Scope	Limited to the program or block where defined.	Global scope,  affects all occurrences in the program.
Debugging	Provides better debugging with recognizable type names.	May lead to debugging issues due to direct replacement.
Type Safety	Provides type safety by creating a new data type.	Lacks type safety; performs textual replacement.
Type Safety	More flexible; can be used with complex data types.	Less flexible; mainly used for constants and simple replacements.