c - how to deallocate the memory allocated to the malloc in following code? -

           int n;            int **arr;            arr = (int**)malloc(n*sizeof(int));            (i=0; i<n; ++i){           arr[i] = malloc(2*sizeof(int));            } 

[edit]

      *** glibc detected *** ./abc: double free or corruption (out): 0x0000000002693370   ======= backtrace: =========  /lib/libc.so.6(+0x775b6)[0x7f42719465b6]  /lib/libc.so.6(cfree+0x73)[0x7f427194ce53]  ./abc[0x405f01]  /lib/libc.so.6(__libc_start_main+0xfd)[0x7f42718edc4d]  ./abc[0x400ee9]  ======= memory map: ======== 00400000-00416000 r-xp 00000000 08:07 392882                               00616000-00617000 r--p 00016000 08:07 392882    

i tried following mentioned answers, got following above mentioned error.what can reason it?

[edit]

the above mentioned problem solved. since there bug in code. now,what not getting improvement in freed memory.what can reason it?

[edit] using modules print memory.following code

     memory_print();      #ifdef check      memory_printleaks();       #endif 

here memory_printleaks() prints demanded memory , freed memory.i getting same value after making changes.

one more remark add is, can call free() anywhere program or required call particular locations place malloc() has been called or @ end of program?

with free. must first free memory pointed @ arr[i] entries, , free memory pointed @ arr (which holds entries). can't other way around, because freeing memory means may no longer use values in memory.

thus:

for (i = 0; < n; ++i) {     free(arr[i]); } free(arr);