Question

I want to convert the type of the pointer ‘p’. Begining ,the type of the pointer p is void .After allocating four bytes of memory for it, I cast pointer type into ‘int’,However ,this doesn’t work . maybe the sentence p=(int *)p doesn’t work.
Please tell me why and solve the problem.thanks.
The coding:

#include<stdio.h>
#include <stdlib.h>

 int main(void)
{
   void *p;
   p=malloc(sizeof(int));
   if(p == NULL)
    {
        perror("fail to malloc");
        exit(1);
    }
    p=(int *)p;
        *p=100;
    printf("the value is : %d\n",*p);

    return 0;
 } 

Answer 1

You’ll have an easier time directly casting the void pointer returned by malloc to an int*

#include<stdio.h>
#include <stdlib.h>

int main(void)
{
   int *p;
   p = malloc(sizeof(int));
   if(p == NULL)
    {
        perror("fail to malloc");
        exit(1);
    }

    *p=100;
    printf("the value is : %d\n",*p);

    return 0;
 }