c - why this function always crashes? -

can tell me why fillpool crashes? maybe there infinite recursion, where?

#include <stdio.h> #include <stdbool.h>  #define n 5  bool isnotvalidindex(int row , int column) {   if((row >= n || row < 0) || (column >= n || column < 0))       return true ;   return false ; }  void fillpool(int row , int column , int picture[n][n]) {   if(isnotvalidindex(row , column))     return ;   if(picture[row][column] == 0)     return ;   picture[row][column] = 2 ;   fillpool(row + 1 , column , picture) ;   fillpool(row - 1 , column , picture) ;   fillpool(row ,column + 1 , picture) ;   fillpool(row , column -1 , picture) ; } 

you have infinite recursion because you're setting value of row/col "2" check "0". you're setting values 2 on , on again. infinite recursion happens because you're calling fillpool "row+1" fillpool "row-1" , infinite recursion (and same thing happen column+1 never reach there).