分配给指针数组结构的元素不起作用（空）

Question

I'm new here and in programming. My problem is when i try to asign a value to a proprerty of a array pointers struct, it does not work. The following code without struct work:

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int *array;
    int size = 10;
    array = malloc(sizeof(int) * size);

    int i;
    for (i = 0; i < size; i++)
    {
        array[i] = i * i;
    }

    for (i = 0; i < size; i++)
    {
        printf("%d\n", array[i]);
    }
}

But when i put struct it does print (null):

#include <stdio.h>
#include <stdlib.h>

typedef struct Person
{
    unsigned char name;
} Person;

int main()
{
    Person *personArray;
    int size = 10;
    personArray = (Person *)malloc(sizeof(int) * size);

    int i;
    for (i = 0; i < size; i++)
    {
        unsigned char name = "Person_name"; //[Warning] initialization makes integer from pointer without a cast
        personArray[i].name = name;
    }

    for (i = 0; i < size; i++)
    {
        printf("%s\n", personArray[i].name); //Print (null)
    }
}

Why this happens? Sorry for anything if I'm new here.

Thank you, the following code work:

#include <stdio.h>
#include <stdlib.h>

typedef struct Person
{
    unsigned char *name;
} Person;

int main()
{
    Person *personArray;
    int size = 10;
    personArray = (Person *)malloc(sizeof(Person) * size);

    int i;
    for (i = 0; i < size; i++)
    {
        unsigned char *name = "Person_name";
        personArray[i].name = malloc(strlen(name) + 1); //[Warning] incompatible implicit declaration of built-in function 'strlen'
        strcpy(personArray[i].name, name); //[Warning] incompatible implicit declaration of built-in function 'strcpy'
    }

    for (i = 0; i < size; i++)
    {
        printf("%s\n", personArray[i].name);
        free(personArray[i].name);
    }

    free(personArray);
}

Answer 1

First of all, here

personArray = (Person *)malloc(sizeof(int) * size);

You probably want sizeof(Person) instead of sizeof(int) . Furthermore, you seem to have some confusion with char and strings. This here:

unsigned char name = "Person_name";

Attempts to assign a string literal to a char . Your compiler should issue a warning. Instead this should be unsigned char *name . And also make the name in Person a pointer. Also note that this makes no copy. If you wanted a copy of the strings, do this instead:

unsigned char *name = "Person_name";
personArray[i].name = malloc(strlen(name) + 1);
strcpy(personArray[i].name, name);

If you do this, free the string when you're done using it, such as after you print it:

free(personArray[i].name);

And (either way) when you're done, don't forget to free the memory of personArray :

free(personArray);