Segmentation fault (core dumped) in C that includes pointers - c

Question

I am working on a homework project and we are using pointers and it seems that those pointer values are changed at some in my program and I can't find that specific spot. rp is the pointer that is changing. I am new to pointers so I tried de dereferencing them in different ways, but I am ultimately unsure.
Here is my code
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
int getMenuChoice();
void generateCoords(int row, int cols, char[][cols], int *rp, int *cp);
int main() {
int myChoice;
int userDifficulty;
srand(time(NULL));
do {
myChoice = getMenuChoice();
if (myChoice == 1) {
printf("\nEnter difficulty (1, 2, or 3): ");
scanf("%d", &userDifficulty);
int gridSize = 2;
gridSize = userDifficulty * 2;
char array[gridSize][gridSize];
preSetBoard(gridSize, gridSize, array);
generateCoords(gridSize, gridSize, array, x, y);
//printf("%d %d", x, y);
}
} while (myChoice != 0);
return 0;
}
int getMenuChoice() {
int userInput;
printf("***MEMORY!***\n");
printf("1 - Play Game\n");
printf("2 - Check Scores\n");
printf("0 - EXIT\n");
scanf("%d", &userInput);
return userInput;
}
void generateCoords(int row, int cols, char array[][cols], int *rp, int *cp) {
_Bool run = 1;
srand(time(NULL));
while (run) {
int place1 = rand() % (row) + 1;
rp = &place1;
//printf("%d\n", *rp);
int place2 = rand() % (row) + 1;
cp = &place2;
//printf("%d\n", *cp);
if (array[*rp][*cp] == 'A') {
run = 0;
}
}
}
The expected output is a number between 1 and 3.

Answer 1

There are multiple issues in the posted code:
You add 1 to the random numbers generated for coordinates: this may cause the program to try and access the 2D array beyond its boundaries. Index values should be >= 0 and < size.
Furthermore, you do not pass addresses of int variables to generateCoords, but x and y which are not defined within the code posted. This does not really pose a problem since you modify the function arguments to point to local variables.
Here is a corrected version:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
int getMenuChoice(void);
void presetBoard(int row, int cols, char[][cols]);
void generateCoords(int row, int cols, char[][cols], int *rp, int *cp);
int main() {
int myChoice, userDifficulty, x, y;
srand(time(NULL));
while ((myChoice = getMenuChoice()) > 0) {
if (myChoice == 1) {
printf("\nEnter difficulty (1, 2, or 3): ");
if (scanf("%d", &userDifficulty) != 1)
break;
int gridSize = userDifficulty * 2;
char array[gridSize][gridSize];
preSetBoard(gridSize, gridSize, array);
generateCoords(gridSize, gridSize, array, &x, &y);
printf("%d %d\n", x, y);
}
}
return 0;
}
int getMenuChoice(void) {
int userInput;
printf("***MEMORY!***\n");
printf("1 - Play Game\n");
printf("2 - Check Scores\n");
printf("0 - EXIT\n");
if (scanf("%d", &userInput) != 1)
userInput = 0;
return userInput;
}
void generateCoords(int rows, int cols, char array[][cols], int *rp, int *cp) {
int col, row;
for (;;) {
row = rand() % rows;
col = rand() % cols;
if (array[row][col] == 'A') {
break;
}
}
/* return found coordinates to the caller */
*rp = row;
*cp = col;
}