Code:
#include<iostream>
using namespace std;
void quadruple(int [], int );
// It's more common to put the prototype outside of any function
int main()
{
const int arraySize=4;
int integer[arraySize], a;
for (a=0; a<arraySize; ++a)
{
cout<<"Enter an integer: ";
cin>>integer[a];
//You need to clear the input stream between numbers
}
quadruple(integer, arraySize);
}
void quadruple(int values[], int arraySize)
{
int a; //You need to declare a in this function if you plan to use it here, too
for (a=0; a<arraySize; ++a)
integer[a]=integer[a]*4;
for (a=0; a<arraySize;++a)
cout<<integer[a]<<endl;
}