pointer being realloc'd was not allocated - c

Question

Actually this is a pure C prog.when i compile with Xcode. error
message says "pointer being realloc'd was not allocated"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int LocateElem(int *p1,int e,int leng1);
void Display(int max, int array[]);
int GetElem(int * p, int pass);
int Union(int *p1,int *p2, int leng1, int leng2);
int ListInsert(int *p, int e, int lengA);
int* GetData(int* pArray, int Array_size);
void Show(int *p, int leng);
void InitList_Sq(int *L);
int *p_A,*p_B;
int m,n;
int main()
{
clock_t begin, end;
double cost;
begin = clock();
printf("How many elements of A u want:");
scanf("%d",&m);
if (m<0) {
printf("Error!");
return 0;
}
printf("How many elements of B u want:");
scanf("%d",&n);
if (n<0) {
printf("Error!");
return 0;
}
p_A=(int *)malloc(m*sizeof(int));
p_B=(int *)malloc(n*sizeof(int));
if (p_A==NULL) {
printf("Error allocating memory!\n"); //print an error message
return 0; //return with failure
}
if (p_B==NULL) {
printf("Error allocating memory!\n"); //print an error message
return 0; //return with failure
}
int *pLast_A, * pLast_B;
printf("Array A is :\n");
pLast_A=GetData(p_A, m);
printf("\nArray B is :\n");
pLast_B=GetData(p_B, n);
int newLeng;
newLeng=Union(p_A,p_B,m,n);
printf("\nThe Union set is :\n");
Show(p_A, newLeng);
free(p_A);
free(p_B);
end = clock();
cost = (double)(end - begin) / CLOCKS_PER_SEC;
printf("\n%lf seconds", cost);
return 1;
}
int* GetData(int* pArray, int Array_size){
int* pFill= pArray;
int count;
srand((unsigned) time(NULL));
for ( count=0; count< Array_size; count++) {
*(pFill+count)=rand()%1000;
printf("%d\t", * (pFill+count));
}
return pFill+count;
}
int Union(int *p1,int *p2, int leng1, int leng2){
for (int count=0; count<leng2; count++) {
int e=GetElem(p2, count);
while(LocateElem(p1, e, leng1)==0){
leng1=ListInsert(p1, e, leng1);
}
}
return leng1;
}
int GetElem(int *p, int pass){
return *(p+pass);
}
int LocateElem(int *p1,int e,int leng1){
for (int count=0; count<leng1; count++)
if (e==*(p1+count))
return 1;
else
return 0;
}
int ListInsert(int *p, int e, int lengA){
lengA+=1;
int* temp;
temp=(int*)realloc(p, lengA*sizeof(int));
if (temp==NULL) {
printf("Error allocating memory!\n"); //print an error message
free(temp);
return 0; //return with failure
}
else{
p=temp;
*(p+lengA-1)=e;
}
return lengA;
}
void Show(int *p, int leng){
for (int count=0; count<leng; count++) {
printf("%d\t", *(p+leng));
}
}
After compilation xcode gives the breakpoint at the line temp=(int*)realloc(p, lengA*sizeof(int)) with signal SIGABRT.

Answer 1

The problem is that here:
int ListInsert(int *p, int e, int lengA){
int* temp;
temp=(int*)realloc(p, lengA*sizeof(int));
...
else {
p=temp; // <<<<< THIS
the new value of p does not propagate back to the ListInsert's caller. This happens because p is passed by value.
You need to turn int *p into int **p.