Cannot assign values to array of pointers in C - arrays

Question

I want to copy my array over to a pointer, so I can sort the array without changing the original. I'm not getting any errors, and am at a dead end. I've tried printing the pointer's contents, but it's always junk data. If anyone could help me it'd be much appreciated.
#include <stdio.h>
void bubbleSort(char *array[], int arrIndex);
void displaySort (char *array[], int arrIndex);
int main (void)
{
int index;
int count = 0;
printf("Enter number of people (0 - 50): ");
scanf("%d", &index);
index -= 1;
char userLastFirst[25][index];
int userAge[index];
//defining pointer
char *namePtr[25][index];
//do while loop, loops while count is less than or equal to the index
do{
printf("Enter name %d (last, first): ", count);
scanf(" %[^\n]s", userLastFirst[count]);
printf("Enter age %d: ", count);
scanf("%d", &userAge[count]);
// printf("\n\n%s %d\n\n", userLastFirst[count], userAge[count]);
count++;
} while (count <= index);
//assigning values to pointer
for(int i = 0; i < index; i++){
namePtr[25][i] = &userLastFirst[25][i];
}
//does not print values of pointer
for(int i = 0; i < index; i++){
printf("value of ptr[%d] = %s\n", i, namePtr[i]);
}
bubbleSort(*namePtr, index);
displaySort(*namePtr, index);
return 0;
}
void bubbleSort(char *array[], int arrIndex)
{
for (unsigned int pass = 0; pass < arrIndex - 1; ++pass) {
for (int i = 0; i < arrIndex - 1; ++i) {
if (array[i] < array[i + 1]) {
int temp = *array[i];
*array[i] = *array[i + 1];
*array[i + 1] = temp;
}
}
}
}
void displaySort(char *array[], int arrIndex)
{
for(int i = 0; i < arrIndex; i++){
printf("%s",*array[i]);
}
}
Sorry it's a lot, but I've looked everywhere, and am not exactly sure what the problem is. I suspect it's how I pass pointers thru the functions, or how I'm using * and & but am not totally sure what I'm doing wrong. The for loop below the one that assigns the array values to the pointer is for testing. It's supposed to print out the values I had given it in the previous for loop, but it doesn't. It just prints junk data.

Answer 1

There are couple of issues here, and since I don't know what exactly you want your final code to look like, I am going to give a few examples of what is wrong and how you could possibly fix that.
char userLastFirst[25][index];
This should be
char userLastFirst[index][25];
You don't want 25 people with names up to index characters in them, but rather index people with names up to 25 characters int them.
char *namePtr[25][index];
should be
char namePtr[index][25];
Same as before + you don't need the * here. Since you decided to go with vla let's stick with it. You would use * and more specifically char ** if you went with malloc/calloc.
namePtr[25][i] = &userLastFirst[25][i];
rather than doing this awkward copying, try:
strcpy(namePtr[i], userLastFirst[i]);
it copies the entire string for you, rather than just a single character. You will need to #include the <string.h> library for that.
void bubbleSort(char *array[], int arrIndex)
The first bubble sort argument should be:
char array[][25] // the same in displaySort
if you want to do it without the hassle of malloc/calloc.
And also don't go with int as your temp type. Rather do char temp[25] and copy them around with strcpy.
And don't compare strings with <, it doesn't work in C. Use strcmp for that.
And that's it for doing it without malloc/calloc, here's an example code:
#include <stdio.h>
#include <string.h>
void bubbleSort(char array[][25], int size);
void displaySort(char array[][25], int size);
int main (void)
{
int num_of_people;
printf("Enter number of people (0 - 50): ");
scanf("%d", &num_of_people);
char original_array[num_of_people][25];
char copied_array[num_of_people][25];
for (int i = 0; i < num_of_people; i++) {
printf("Enter name %d (last, first): ", i);
scanf(" %[^\n]s", original_array[i]);
}
for(int i = 0; i < num_of_people; i++){
strcpy(copied_array[i], original_array[i]);
}
bubbleSort(copied_array, num_of_people);
displaySort(copied_array, num_of_people);
return 0;
}
void bubbleSort(char array[][25], int size)
{
for (int i = 0; i < size - 1; ++i) {
for (int j = 0; j < size - 1 - i; ++j) {
if (strcmp(array[j], array[j + 1]) > 0) {
char temp[25];
strcpy(temp, array[j]);
strcpy(array[j], array[j + 1]);
strcpy(array[j + 1], temp);
}
}
}
}
void displaySort(char array[][25], int size)
{
for(int i = 0; i < size; i++){
printf("%s\n",array[i]);
}
}
and the program work like this:
Enter number of people (0 - 50): 4
Enter name 0 (last, first): Kowalski, Jan
Enter name 1 (last, first): Kowalska, Anna
Enter name 2 (last, first): Nowak, Miłosz
Enter name 3 (last, first): Amper, Ohm
Amper, Ohm
Kowalska, Anna
Kowalski, Jan
Nowak, Miłosz
I hope this is something you wanted to achieve.