Passing pointer to pointer and reallocate space

Question

I post this sample code in order to explain my problem. I'm trying to passing among functions a pointer to integer. If you compile & run this code you'll see that strange numbers appears and I can't get why. I think it's a bad use of realloc(). If anybody could give a hint or maybe redirect me to some questions similar to this I'll appreciate. I search for this problem but I can't find anything similar.

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


void myFunction(int **output);


int main(){

    int *indices;
    myFunction(&indices);

    printf("{");
    for(int i=0;i<10;i++){//suppose also for some mysterious reasons that I know min_size in the main
        printf("%i,", indices[i]);
    }
    printf("}\n");

    return 0;
}


void myFunction(int **output){

    int size = 130;//allocating big amount of space
    int* indices = malloc(sizeof(int)*size);

    //...start doing mysterious stuffs....
    int min_size = 10; 
    for(int i=0;i<min_size;i++){
        indices[i] = i;//just for saving something
    }
    //...end doing mysterious stuffs...

    //now for some reasons I know I need only min_size elements and all other are wasting space so I reallocate
    indices = realloc(indices,min_size);//resizing in order to save space

    *output = indices;
}

Answer 1

You are using realloc incorrectly. The size of the reallocated extent must be

min_size * sizeof( int )

Here you are

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

void myFunction(int **output);


int main( void )
{

    int *indices;
    myFunction(&indices);

    printf("{");
    for(int i=0;i<10;i++){//suppose also for some mysterious reasons that I know min_size in the main
        printf("%i,", indices[i]);
    }
    printf("}\n");

    return 0;
}


void myFunction(int **output){

    int size = 130;//allocating big amount of space
    int* indices = malloc(sizeof(int)*size);

    *output = indices;
    // ^^^^^^^^^^^^^^^

    //...start doing mysterious stuffs....
    int min_size = 10; 
    for(int i=0;i<min_size;i++){
        indices[i] = i;//just for saving something
    }
    //...end doing mysterious stuffs...

    //now for some reasons I know I need only min_size elements and all other are wasting space so I reallocate

    indices = realloc(indices, min_size * sizeof( int ) );//resizing in order to save space
    //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    if ( indices ) *output = indices;
    //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}   

The program output is

{0,1,2,3,4,5,6,7,8,9,}