Assertion failure :: malloc -

i running code in coding site , got following error:

solution: malloc.c:2369: sysmalloc: assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed. aborted (core dumped)

code:

#include <stdio.h> #include <string.h> #include <math.h>  typedef struct cell {     int x;     int y;     struct cell *prevcell;     struct cell *nextcell; }cell;   /* head ends here */ void nextmove(int x, int y, int pacman_x, int pacman_y, int food_x, int food_y, char grid[x][y]){     //logic here         int i=pacman_x;     int j=pacman_y;       cell *top,*node;     top = null;      while(grid[i][j] != '.')     {         node = null;         //up         if(i != 0 && grid[i-1][j] != '%')         {             if(grid[i][j] != 'd')             {                 printf("%d %d\n",i,j);                 grid[i][j]='d';             }             //push             node = (cell*)malloc(sizeof(node));             node->x=i;             node->y=j;             node->prevcell=top;             node->nextcell=null;             if(top != null)                 top->nextcell=node;             top=node;              i=i-1;         }         //left         else if(j != 0 && grid[i][j-1] != '%')         {             if(grid[i][j] != 'd')             {                 printf("%d %d\n",i,j);                 grid[i][j]='d';             }             //push             node = (cell*)malloc(sizeof(node));             node->x=i;             node->y=j;             node->prevcell=top;             node->nextcell=null;             if(top != null)                 top->nextcell=node;             top=node;              j=j-1;         }         //right         else if(j != y-1 && grid[i][j+1] != '%')         {             if(grid[i][j] != 'd')             {                 printf("%d %d\n",i,j);                 grid[i][j]='d';             }             //push             node = (cell*)malloc(sizeof(node));             node->x=i;             node->y=j;             node->prevcell=top;             node->nextcell=null;             if(top != null)                 top->nextcell=node;             top=node;              j=j+1;         }         //down         else if(i != x-1 && grid[i+1][j] != '%')         {             if(grid[i][j] != 'd')             {                 printf("%d %d\n",i,j);                 grid[i][j]='d';             }             //push             node = (cell*)malloc(sizeof(node));             node->x=i;             node->y=j;             node->prevcell=top;             node->nextcell=null;             if(top != null)                 top->nextcell=node;             top=node;              i=i+1;         }         else         {             //pop             top=top->prevcell;             free(top->nextcell);             i=top->x;             j=top->y;         }     }  } /* tail starts here */ int main() {      int x, y;     int pacman_x, pacman_y;     int food_x, food_y;     scanf( "%d %d", &pacman_x, &pacman_y);     scanf( "%d %d", &food_x, &food_y);     scanf( "%d %d", &x, &y);     char grid[x][y];      for( int i=0; i<x; i++) {         scanf("%s[^\\n]%*c", grid[i]);     }     nextmove( x, y, pacman_x, pacman_y, food_x, food_y, grid);     return 0; } 

i not getting issue. help??

your scanf() format wrong.

scanf("%s[^\\n]%*c", grid[i]); 

this saying scanf() for
1) string (%s)
2) character '['
3) character '^'
4) character '\'
5) character 'n'
6) character ']'
7) char (%*c), not store it
might want drop 's'

scanf("%[^\\n]%*c", grid[i]); 

idea:

char buf[80]; fgets(buf, sizeof(buf)-1, stdin); sscanf(buf, "%[^\\n]", grid[i]); 

i find safer separate input parsing.

further, have

char grid[x][y]; 

this appears dynamically allocation of "grid" based on size of x & y. not c (unless new feature). need ask, compiler using?