How to delete structure entries and use realloc to free memory

Question

I am trying to delete structure entries and then use realloc to free the memory. My structure is

typedef struct person {
    char fname[20];
    char lname[20];
    int number[10];
}person;

Im using a function to delete inputted entries

void delInfo(int*,person*);

The way the delete function is supposed to work is by locating said entry, shift back all records after that, then freeing last record with realloc. The code for it so far looks like this

void delInfo(int *num_entries,person*contacts){
    char delfirst[20];
    char dellast[20];

    printf("\n First Name: ");
    scanf("%s",delfirst);
    printf(" Last Name: ");
    scanf("%s",dellast);
    int i=0;

    for (i=0; i<*num_entries;i++){
        if (delfirst==contacts[i].fname && dellast==contacts[i].lname){

        }
    }
}

So far I can search for a match with the first and last name, but dont know what happens if I move every entry "down one." If matching entry is contacts[i] something like

int c;
for (c=i+1;c<*num_entries;c++){
    contacts[i].fname=contacts[c].fname;
    contacts[i].lname=contacts[c].lname;
    contacts[i].number=contacts[c].number;
}
contacts=(person*)realloc(contacts,sizeof(contacts)*(num_entries-1));

If I do that to all entries AFTER the one I plan on deleting, do they just "overwrite" the entry I want to delete, then I can realloc to shorten the structure array and essentially free the memory?

Answer 1

If i is the index of the entry that you want to delete, all you really need to do is:

for (c = i; c < *num_entries - 1; c++)
    contacts[c] = contacts[c+1];

Then you can reallocate for the smaller dynamic array. Structs can be assigned to compatible structs, so you don't need to assign the fields of the structs individually.