C dynamic memory allocation array -

my program has 3 int arrays (pointers) declared in main function. user enters length of array a, filled random numbers.

then, function called takes 3 arrays arguments. takes numbers array a , puts them array b, , odd numbers c. sizes of b , c need same number of elements. elements of b printed.

#include <stdio.h> #include <stdlib.h> #include <time.h>  int vela, velb, velc; //the sizes of arrays  void napravi(int a[], int *b, int *c);  void main() {     int *a, *b, *c;     int i;     srand(time(null));      printf("enter array lenght:");      scanf("%d", &vela);     getchar();      = (int*)calloc(vela, sizeof(int));     b = (int*)malloc(4); //i have initialize variable in order pass argument ?     c = (int*)malloc(4);      for(i = 0; < vela; i++) {         a[i] = rand() %101;     }      napravi(a, b, c);      for(i = 0; < velb; i++) {         printf("%d  ", b[i]);     }      free(a); //  free(b); //windows has triggered breakpoint in .exe //  free(c);     getchar(); }  void napravi(int a[], int *b, int *c) {     int i;     int j = 0, k = 0;      for(i = 0; < vela; i++) {         if(a[i] % 2 == 0) {             j++;         }         else {             k++;         }     }     free(b);     free(c);     b = (int*)calloc(j, sizeof(int));     c = (int*)calloc(k, sizeof(int));       j = 0; k = 0;      for(i = 0; < vela; i++) {         if(a[i] % 2 == 0) {             b[j] = a[i]; //          printf("\n%d | %d", a[i], b[j]);             j++;         }         else {             c[k] = a[i];             k++;         }     }     velb = j;     velc = k; } 

there 2 problems code.

• first, if user enters value bigger around ~420, starts print junk values -17987777...
• second, when attempt free(b) , free(c) @ end, program crashes error "windows has triggered breakpoint in my.exe".

try this

int main(void) {     int *a, *b, *c;     int i;     srand(time(null));      printf("enter array lenght:");      scanf("%d", &vela);     getchar();      = (int*)calloc(vela, sizeof(int));     //b = null;//there no need set value     //c = null;//null better malloc(4)      for(i = 0; < vela; i++) {         a[i] = rand() %101;     }      napravi(a, &b, &c);      for(i = 0; < velb; i++) {         printf("%d  ", b[i]);     }      free(a);     free(b);     free(c);     getchar();     return 0; }  void napravi(int a[], int **b, int **c) {     int i;     int j = 0, k = 0;      *b = *c = null;     velb = velc = 0;     if(a == null || vela == 0)         return;      for(i = 0; < vela; i++) {         if(a[i] % 2 == 0) {             j++;         }     }      if(velb = j)         *b = (int*)malloc(velb * sizeof(int));     if(velc = vela - velb)         *c = (int*)malloc(velc * sizeof(int));       j = 0; k = 0;      for(i = 0; < vela; i++) {         if(a[i] % 2 == 0)             (*b)[j++] = a[i];         else             (*c)[k++] = a[i];     } }