Create 2-D Array and Set Values - c

Question

I am trying to write a C program that generates R files that solve systems of linear equations. In main, I have six nested for loops to get every iteration of where the coefficients are integers 0 - 9:
ax + by + c = dx + ey + f
a_2x + b_2y + c_2 = d_2x + e_2y + f
Each equation is a array of 6 integer coefficients. I set the values of the coefficients in my main function before passing it to generateContentForSystems.
However, my print statement returns:
value of numx:-000-0 value of numy:000-0 value of numz:00-0 value of numx_2:0-0 value of numy_2:-0 value of numz_2:0
I believe this is because of bad pointer arithmetic. I am now trying to and from a pointer to an array (in main) and have an array of arrays.
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "scaffold.c"
void * generateContentForSystems(int * row1, int * row2) {
static int index = 0;
int x = row1[0] - row1[3];
int y = row1[1] - row1[4];
int z = row1[5] - row1[2];
int x_2 = row2[0] - row2[3];
int y_2 = row2[1] - row2[4];
int z_2 = row2[5] - row2[2];
int prod1 = x * y_2;
int prod2 = x_2 * y;
int determinant = prod1 - prod2;
if (determinant != 0) {
printf("the value of determinant: %d", determinant);
char * error1;
char Q[1000];
strcpy(Q, "emake <- function(){\noptions(\"warn\"=-1)\ne <- 0\nfor (n in 0:2000){\ne <- e+ 1/(factorial(n))\n}\nreturn(e)\n}\ne <- emake()\n");
char numx[1];
char numy[1];
char numz[1];
char numx_2[1];
char numy_2[1];
char numz_2[1];
sprintf(numx, "%d", x);
sprintf(numy, "%d", y);
sprintf(numz, "%d", z);
sprintf(numx_2, "%d", x_2);
sprintf(numy_2, "%d", y_2);
sprintf(numz_2, "%d", z_2);
//debug:
printf("value of numx:%s value of numy:%s value of numz:%s value of numx_2:%s value of numy_2:%s value of numz_2:%s", numx, numy, numz, numx_2, numy_2, numz_2);
strcat(Q, "A = array(c(");
strcat(Q, numx);
strcat(Q, ", ");
strcat(Q, numx_2);
strcat(Q, ", ");
strcat(Q, numy);
strcat(Q, ", ");
strcat(Q, numy_2);
strcat(Q, "), dim = c(2,2,1))\n");
strcat(Q, "b = c(");
strcat(Q, numz);
strcat(Q, ", ");
strcat(Q, numz_2);
strcat(Q, ")\n");
strcat(Q, "solve(A[,,1],b)\n");
char filename[100];
char snum[5];
itoa(index, snum);
index++;
strcpy(filename, "practice/");
strcat(filename, snum);
strcat(filename, ".R");
FILE * F = fopen(filename, "w");
fputs(Q, F);
fclose(F);
char path[1024];
char command[300];
strcpy(command, "Rscript ");
strcat(command, "practice/");
debug("After Rscript formation");
strcat(command, snum);
strcat(command, ".R");
FILE * fp = popen(command, "r");
if (!fp) { //validate file is open
return NULL;
}
while (fgets(path, sizeof(path) - 1, fp) != NULL) {
debug("in Primary While Loop");
fflush(stdout);
printf("the solution: %s", path);
if (strstr(path, ".") > strstr(path, "with absolute error") || strstr(path, ".5 ") != NULL) {
printf("answer was accepted");
}
}
}
}
int main() {
int arrayIndexes = 0;
int ** myArray = malloc(1 * sizeof( * myArray));
for (int a = 0; a < 10; a++) {
for (int b = 0; b < 10; b++) {
for (int c = 0; c < 10; c++) {
for (int d = 0; d < 10; d++) {
for (int e = 0; e < 10; e++) {
for (int f = 0; f < 10; f++) {
myArray[arrayIndexes] = malloc(6 * sizeof(int));
myArray[arrayIndexes][0] = a;
myArray[arrayIndexes][1] = b;
myArray[arrayIndexes][2] = c;
myArray[arrayIndexes][3] = d;
myArray[arrayIndexes][4] = e;
myArray[arrayIndexes][5] = f;
if (arrayIndexes > 0) {
for (int i = 0; i < arrayIndexes; i++) {
generateContentForSystems(myArray[arrayIndexes], myArray[i]);
}
}
++arrayIndexes;
myArray = realloc(myArray, (arrayIndexes + 1) * sizeof( * myArray));
}
}
}
}
}
}
for (int n = 0; n = arrayIndexes; n++) {
free(myArray[n]);
}
free(myArray);
return 0;
}

Answer 1

Your number strings are not long enough:
char numx[1];
char numy[1];
char numz[1];
char numx_2[1];
char numy_2[1];
char numz_2[1];
A string consists of a sequence of characters plus a null terminating byte. So even a single digit needs an array size of at least 2. When you use sprintf to write the text representation of a number to one of these arrays you write past the end of the array. This invokes undefined behavior.
These arrays need to be large enough to accommodate whatever value you may pass in, including a negation sign if needed.
char numx[10];
char numy[10];
char numz[10];
char numx_2[10];
char numy_2[10];
char numz_2[10];