typedef

Learn to give new names to types with typedef.

Aliases with typedef

The typedef keyword gives a new name to an existing type. It is used to shorten long type names and make code more meaningful:

typedef unsigned int uint;
typedef double Distance;

Now uint and Distance can be used just like unsigned int and double. The compiler treats them the same; only readability improves.

typedef and #define look similar but work differently:

Always prefer typedef for type aliases. #define is for constant values; it lacks type context and is error-prone.

Define typedef double Distance;. Declare a Distance variable (5.5 for example) and print it with printf using %lf.

Show example solution

#include <stdio.h>

typedef double Distance;

int main(void) {
    Distance d = 5.5;
    printf("%lf", d);
    return 0;
}

typedef name

typedef double ____;

Show answer

typedef double Distance;