Thread: program crashes, no idea why

this is the source code, the compiler(myngw,gcc) doesnt warn me about anything, but when i start the program it crashes.

Code:

#include <stdio.h>
#include <stdlib.h>
 
int matrixmax(int height,int width,int** tomb){
    int i,j,max=0;
    for(i=0;i<height;i++){
           for(j=0;i<width;j++){
            if(tomb[i][j]>max){
                max=tomb[i][j];
            }           
       }
   }
   return max;
}


int main() {
   int i,j,height=2,width=3;
   int** tomb;
   tomb=malloc(height*sizeof(int*));
   for(i=0;i<height;i++){
           tomb[i]=malloc(width*sizeof(int));


   }
   for(i=0;i<height;i++){
       for(j=0;j<width;j++){
           tomb[i][j]=rand()%100+1;
       }
   }


    printf("%d",matrixmax(height,width,tomb));




   for(i=0;i<height;i++){
       free(tomb[i]);
   }
   free(tomb);


}

the program allocates some memory for a 2d array, and then a function finds the max value and returns it.

Well here is the problem:

Code:

(gdb) run
Starting program: C:\Users\jk\Desktop\sandbox.exe
[New Thread 11136.0x15f0]
[New Thread 11136.0x187c]

Program received signal SIGSEGV, Segmentation fault.
0x00000000004015ff in matrixmax (height=2, width=3, tomb=0xb61640)
    at sandbox.c:8
8                   if(tomb[i][j]>max){
(gdb) print i
$1 = 0
(gdb) print j
$2 = 3680

See how j is really big? That means that the matrix is trying to access memory it doesn't own. It can cause a segmentation fault.

As for why j is really big, look carefully at the inner loop in matrixmax().

Code:

 for(j=0;i<width;j++){

You probably meant j < width. What you have written makes the loop work very differently.

Indeed, didnt notice that at all.
Thanks for the fast response!