Thread: Is this kind of dynamic memory allocation good?

Hi! I just started learning a bit more intermediate C and I am implementing the Convex Hull algorithm. Now the problem I face is I don't want the user to have to enter the number of points he has. So this is how i currently handle that:

First there is an array dynamically allocated where the user input is stored.
It keeps reading user input until user enters -1.
Everytime user enters a number that is not -1 size is increased by one.
Then a new array is allocated size*sizeof(int)
All the known data from readbuffer is then transfered to the new array and the readbuffer is freed.

If I understand this correctly the program uses a lot of memory at the begging then a lot is freed.

NOTE: init_memsize defines the max amount of points allowed. I know that I need 2 dimension to define a point but this question is purely about memory and efficiency.

CODE:

Code:

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


int main(){
    int size = 0;
    int init_memsize = 100000*sizeof(int);
    int* readbuffer = (int*) malloc(init_memsize);
    bool endread = false;
    int temp;
    while(!endread){
        scanf("%d", &temp);
        if(temp>0){
            readbuffer[size++]=temp;
        }else{
            endread = true;
        }
    }
    int memsize = size*sizeof(int);
    int* data = (int*) malloc(memsize);
    for(int i = 0; i<=size; i++){
        data[i] = readbuffer[i];
    }
    free(readbuffer);
    /*Actual alogrithm code would go here*/
    free(data);
}

You should also check for NULL to see if realloc or malloc failed.

Tim S.