x.c

#include <stdio.h>
#include "cs50.h"
#include <math.h>

void printX(int dimension)
{
//    dimension -= 2;
    if ((dimension % 2 == 0) || (dimension < 3 || dimension > 23)) return;

    if (dimension == 3){
        printf("***\n***\n***");
        return;
    }


    int dim = dimension - 2;
    char x[dim][dim];
    int i;
    int j;

    i = 0;
    j = 0;

    for (i = 0; i < dim; i++){
        for (j = 0; j < dim; j++){
            if ((i == (dim-1-j)) ||(i == j)) x[i][j] = '*';
            else x[i][j] = ' ';
        }
    }


    for (i = 0; i < dimension; i++) printf("*");
    printf("\n");
    for (i = 0; i < dim; i++){
        for (j = 0; j < dim; j++){
            if (j == 0){
                printf("*");
                printf("%c", x[i][j]);
            } else if (j == dim - 1){
                printf("%c", x[i][j]);
                printf("*");
            } else {
                printf("%c", x[i][j]);
            }
        }
        printf("\n");
    }
    for (i = 0; i < dimension; i++) printf("*");
}

int main(void)
{
    int dim = GetInt();
    printX(dim);
}