🟡 Intermediate · Lesson 32

typedef in C

typedef

What is typedef?

typedef is used to create a new name or alias for an existing data type. It improves readability, especially with structures and pointers.

Syntax

typedef existing_type new_name;

Basic typedef

C Language

#include <stdio.h>

typedef unsigned int uint;
typedef long long ll;

int main() {
    uint age = 25;
    ll population = 1400000000LL;

    printf("Age = %u\n", age);
    printf("Population = %lld", population);
    return 0;
}

typedef with struct

Without typedef, we must write struct Student each time. With typedef, we can write only Student.

C Language

#include <stdio.h>

typedef struct {
    int roll;
    char name[30];
    float marks;
} Student;

int main() {
    Student s1 = {101, "Aman", 88.5};
    printf("%d %s %.1f", s1.roll, s1.name, s1.marks);
    return 0;
}

101 Aman 88.5

typedef with Pointer

C Language

typedef int* IntPtr;

int main() {
    int x = 10;
    IntPtr p = &x;
    printf("%d", *p);
    return 0;
}

⚠️ Pointer typedef caution

IntPtr a, b; makes both a and b pointer variables, but normal int *a, b; makes only a a pointer.

Summary

typedef creates an alias for existing type
It does not create a new data type internally
Very useful with structures
Improves readability in large programs
Use clear names like Student, uint, Node

typedef क्या है?

typedef existing data type का नया नाम या alias बनाने के लिए use होता है। इससे code readable बनता है।

Syntax

typedef existing_type new_name;

Basic typedef

C Language

typedef unsigned int uint;
typedef long long ll;

uint age = 25;
ll population = 1400000000LL;

struct के साथ typedef

C Language

typedef struct {
    int roll;
    char name[30];
    float marks;
} Student;

Student s1 = {101, "Aman", 88.5};

Pointer के साथ typedef

C Language

typedef int* IntPtr;
int x = 10;
IntPtr p = &x;

⚠️ ध्यान दें

Pointer typedef का नाम clear रखें ताकि confusion न हो।

सारांश

typedef existing type का alias बनाता है
Internal नया type नहीं बनता
Structures के साथ बहुत useful है
Code clean और readable बनता है
Clear names use करें जैसे Student, Node, uint

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