Question

how to use struct?

Answer 1

A structure holds data that logically belong together. E.g. a person would have a name and an age and we'd always need to handle this information together. Then we can define a Person structure. For ease of use, we can also create a type definition: TPerson.

The code would look like this in C:

#include <stdio.h>

struct Person
{
    char name[64];
    unsigned char age;
};

typedef struct Person TPerson;

void PrintPerson(TPerson person)
{
    printf("Name: %s\n", person.name);
    printf("Age:  %d\n", person.age);
}

int main()
{
    struct Person person = { "John Doe", 30 };

    PrintPerson(person);

    return 0;
}

One can also unify the structure definition and the type definition by creating an anonymous structure and assigning a name to it via typedef:

typedef struct
{
    char name[64];
    unsigned char age;
} Person;

Structures only hold data, no functionality. For functions, you'd need a class, which is a C++ feature (and other object-oriented languages).

Answer 2

#include <stdio.h>

struct Person
{
    char name[64];
    unsigned char age;
};

typedef struct Person TPerson;

void PrintPerson(TPerson person)
{
    printf("Name: %s\n", person.name);
    printf("Age:  %d\n", person.age);
}

int main()
{
    struct Person person = { "John Doe", 30 };

    PrintPerson(person);

    return 0;
}

Answer 3

typedef struct
{
    char name[64];
    unsigned char age;
} Person;