Thread: Newb Question concerning sizeof() function

I wrote a simple program that takes in 5 numbers into an array and then spits them back at you. Except that if the number inputted by the user is less than 10, it is doubled.

Simple enough. What I don't understand is why when I run the sizeof() function in my doubleA function, it returns the size of the array as 4. I assume it has something to do with its int value, but the sizeof() works fine in the main().

Halp?

Code:

#include <stdio.h>

void doubleA(int a[]);

main()
{

        int array[5];
        int i;

        printf("Please enter 5 numbers: ");

        for(i=0; i<5; i++)
                scanf("%d", &array[i]);
        
         // My custom function
        doubleA(array);

        for(i=0; i<5; i++)
                printf("The %d number you printed was %d\n", i+1, array[i]);
        // prints sizeof() the array
        printf("size of array[] in main() function: %d\n", sizeof(array));
}

void doubleA(int a[])
{

        int i, arraysize;
        arraysize = sizeof(a)/sizeof(int);
        //prints sizeof() the array
        printf("size of a[] in doubleA = %d\n", sizeof(a));
        for (i=0; i<5; i++)
                if (a[i] <10)
                        a[i] *= 2;
}