CODEWITHSUNDEEP
carraysmatrixnullmultidimensional-array
Santiago Páez
Santiago Páez

Reputation: 13

How to know if a location is out of my 2D array?

I need to know if a location of a 2D array is out of it. For example i got a 8x8 array and the user needs to add a number in a location, for example MyArray[3][7] but first i need to verify if that location is in my array. so... can i ask that like this?

if (MyArray[x - 1][y - 1]==NULL){
  printf("Give me another location: \n");
  .
  .
  .
}

Upvotes: 0

Views: 58

Answers (2)

Patricio S
Patricio S

Reputation: 2130

If the value of x and y are entered by the user then you could do something like this:

#include <stdio.h>

int main() {
    int MyArray[8][8];

    int x, y;

    printf("Give me a location: ");
    scanf("%d %d", &x, &y);

    while (x < 0 || x > 7 || y < 0 || y > 7) {
        printf("Give me another location: ");
        scanf("%d %d", &x, &y);
    }

    return 0;
}

Otherwise the program could try to access to a memory space that the program shouldn't touch and try to check if it is NULL.

Upvotes: 2

Colin vH
Colin vH

Reputation: 537

You will need to pass around the dimensions of the array along with the array itself, and do bounds checking the dumb mathy way:

if (x < 0 || x >= xlen || y < 0 || y >= ylen) {...

Upvotes: 1

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