Test Swap Functions, C++ (gcc)

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#include <iostream>
using namespace std;

void swap0(int x, int y);
void swap1(int& x, int& y);
void swap2(int* x, int* y);
void swap3(int* x, int* y);
void show0(int&a, int&b);
void show1(int&a, int&b);
void show2(int&a, int&b);
void show3(int&a, int&b);
int main() {
    void (*pFunc[])(int &a,int& b) = {show0,show1,show2,show3};
    
    std::cout << "Below sizeof(*pFunc)="<< sizeof(*pFunc)<<" functions will be called to test!" <<std::endl;
    
    for (int i(0); i < sizeof(*pFunc); i++) {
        int i1 = 1111, j1 = 2222;
        std::cout << "calling function show"<<i+1<<"("<<i1<<","<<j1<<"):--------------------------------" << std::endl;
        pFunc[i](i1,j1);
    }
    return 0;
}

void swap0(int x, int y){
    int temp;
    temp = x; 
    x = y;    
    y = temp; 
    return;
}
void swap1(int& x, int& y){
    int temp;
    temp = x; 
    x = y;    
    y = temp; 
    return;
}
void swap2(int* x, int* y){
    int* temp;
    temp = x;
    x = y;   
    y = temp;
    return;
}
void swap3(int* x, int* y)
{
    int temp = *x;
    *x = *y;
    *y = temp;
    return;
}
void show0(int &a, int &b) {
    cout << "Before Swap:a(" << std::hex << &a << ")="<<std::dec<< a << ",b(" << std::hex << &b << ")=" << std::dec << b << endl;
    swap0(a, b); 
    cout << "After Swap:a(" << std::hex << &a << ")=" <<std::dec<<a << ",b(" << std::hex << &b << ")=" << std::dec << b << endl;
}
void show1(int& a, int& b) {
    cout << "Before Swap:a=" << a << ",b=" << b << endl;
    swap1(a, b);
    cout << "After Swap:a=" << a << ",b=" << b << endl;
}
void show2(int& a, int& b) {
    cout << "Before Swap:a=" << a << ",b=" << b << endl;
    swap2(&a, &b);  
    cout << "After Swap:a=" << a << ",b=" << b << endl;
}
void show3(int& a, int& b) {
    cout << "Before Swap:a(" << std::hex << &a << ")=" << std::dec << a << ",b(" << std::hex << &b << ")=" << std::dec << b << endl;
    swap3(&a, &b);
    cout << "After Swap:a(" << std::hex << &a << ")=" << std::dec << a << ",b(" << std::hex << &b << ")=" << std::dec << b << endl;
}

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Compilation time: 0.62 sec, absolute running time: 0.18 sec, cpu time: 0.01 sec, memory peak: 5 Mb, absolute service time: 0,91 sec