Flexible array member not getting copied when I make a shallow copy of a struct

Question

I have made a shallow copy a struct I have in the following manner:

struct Student{
        char *name;
        int age;
        Courses *list;  //First cour         


        

Answer 1

In your code snippet the structure declaration is wrong. I think you mean a typedef of a structure instead of declaring an object of the structure.

For example

typedef struct Student
^^^^^^^
{
    char *name;
    int age;
    Courses *list;  //First course (node)
    struct Student *friends[];   //Flexible array memeber stores other student pointers
    ^^^^^^^^^^^^^^
} Student;

This call of malloc is also wrong

Student *oneCopy = malloc(sizeof(one) + 20*sizeof(Student*));

There should be

Student *oneCopy = malloc(sizeof( *one ) + 20*sizeof(Student*));
                                  ^^^^^

Here is a demonstrative program that shows how the function can be written

#include 
#include 
#include 

typedef struct Student
{
    char *name;
    int age;
//    Courses *list;  //First course (node)
    struct Student *friends[];   //Flexible array memeber stores other student pointers
} Student;

Student * shallowCopy( const Student *one, size_t friends )
{
    Student *oneCopy = malloc( sizeof( Student ) + friends * sizeof( Student * ) );

    *oneCopy = *one;

    memcpy( oneCopy->friends, one->friends, friends * sizeof( Student * ) );

    return oneCopy;
}

int main( void )
{
    Student *one = malloc( sizeof( Student ) + sizeof( Student * ) );

    one->friends[0] = malloc( sizeof( Student ) );

    one->friends[0]->age = 20;

    Student *oneCopy = shallowCopy( one, 1 );

    printf( "Age = %d\n", oneCopy->friends[0]->age );

    free( one->friends[0] );
    free( one );
    free( oneCopy );
}    

Its output is

Age = 20

Take into account that it is desirable that the structure also contains a data member that will store the number of elements in the flexible array.:)