How to use typedef in C++

In C++, the keyword typedef is used to create aliases for existing data types, to facilitate code readability and maintenance.

They are especially suitable for simplifying the declaration of complex types (such as those involving heavy use of pointers).

Besides improving readability, it also facilitates portability between platforms (for example, by creating aliases for variable types with different names)

Basic Syntax

The basic syntax of typedef is as follows

typedef data_type alias_name;

For example,

typedef unsigned long ulong;

Common Uses of typedef

Aliases for Simple Data Types

The most basic use of typedef is to create aliases for simple data types, such as int, char, float, etc.

typedef int entero;
typedef float real;
typedef char caracter;

Now, you can use entero, real, and caracter instead of int, float, and char, respectively.

Aliases for Pointers

typedef is especially useful for creating aliases for pointers, which can significantly improve readability.

typedef int* intPtr;

Aliases for Structured Types

When working with structures (structs), typedef can greatly simplify their use and declarations.

typedef struct {
    int x;
    int y;
} Point;

Point p1;
p1.x = 10;
p1.y = 20;

Practical Examples

For more complex data types, such as function pointers or arrays, typedef can make declarations much more manageable.

typedef void (*CallbackFunction)(int, int);

void myFunction(int a, int b) {
    std::cout << "a: " << a << ", b: " << b << std::endl;
}

int main() {
    CallbackFunction callback = myFunction;
    callback(5, 10);
    return 0;
}

typedef int Matrix3i[3][3];

Matrix3i matrix = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9}
};