C++ Functions用法及代碼示例

// C++ Program to demonstrate working of a function
#include <iostream>
using namespace std;
// Following function that takes two parameters 'x' and 'y'
// as input and returns max of two input numbers
int max(int x, int y)
{
    if (x > y)
        return x;
    else
        return y;
}
// main function that doesn't receive any parameter and
// returns integer
int main()
{
    int a = 10, b = 20;
    // Calling above function to find max of 'a' and 'b'
    int m = max(a, b);
    cout << "m is " << m;
    return 0;
}

// C++ Program to show function that takes
// two integers as parameters and returns
// an integer
int max(int, int);
// A function that takes an int
// pointer and an int variable
// as parameters and returns
// a pointer of type int
int* swap(int*, int);
// A function that takes
// a char as parameter and
// returns a reference variable
char* call(char b);
// A function that takes a
// char and an int as parameters
// and returns an integer
int fun(char, int);

// C++ Program to demonstrate function definition
#include <iostream>
using namespace std;
void fun(int x)
{
    // definition of
    // function
    x = 30;
}
int main()
{
    int x = 20;
    fun(x);
    cout << "x = " << x;
    return 0;
}

// C++ Program to demonstrate working of
// function using pointers
#include <iostream>
using namespace std;
void fun(int* ptr) { *ptr = 30; }
int main()
{
    int x = 20;
    fun(&x);
    cout << "x = " << x;
    return 0;
}

recursionfunction()
{
    recursionfunction(); // calling self function
}

#include <iostream>
using namespace std;
void printMin(int arr[5]);
int main()
{
    int ar[5] = { 30, 10, 20, 40, 50 };
    printMin(ar); // passing array to function
}
void printMin(int arr[5])
{
    int min = arr[0];
    for (int i = 0; i < 5; i++) {
        if (min > arr[i]) {
            min = arr[i];
        }
    }
    cout << "Minimum element is: " << min << "\n";
}
// Code submitted by Susobhan Akhuli

// program of function overloading when number of arguments
// vary
#include <iostream>
using namespace std;
class Cal {
public:
    static int add(int a, int b) { return a + b; }
    static int add(int a, int b, int c)
    {
        return a + b + c;
    }
};
int main(void)
{
    Cal C; // class object declaration.
    cout << C.add(10, 20) << endl;
    cout << C.add(12, 20, 23);
    return 0;
}
// Code Submitted By Susobhan Akhuli

// Program of function overloading with different types of
// arguments.
#include <iostream>
using namespace std;
int mul(int, int);
float mul(float, int);
int mul(int a, int b) { return a * b; }
float mul(double x, int y) { return x * y; }
int main()
{
    int r1 = mul(6, 7);
    float r2 = mul(0.2, 3);
    cout << "r1 is : " << r1 << endl;
    cout << "r2 is : " << r2 << endl;
    return 0;
}
// Code Submitted By Susobhan Akhuli

#include <iostream>
using namespace std;
void fun(int);
void fun(float);
void fun(int i) { cout << "Value of i is : " << i << endl; }
void fun(float j)
{
    cout << "Value of j is : " << j << endl;
}
int main()
{
    fun(12);
    fun(1.2);
    return 0;
}
// Code Submitted By Susobhan Akhuli

#include <iostream>
using namespace std;
void fun(int);
void fun(int, int);
void fun(int i) { cout << "Value of i is : " << i << endl; }
void fun(int a, int b = 9)
{
    cout << "Value of a is : " << a << endl;
    cout << "Value of b is : " << b << endl;
}
int main()
{
    fun(12);
    return 0;
}
// Code Submitted By Susobhan Akhuli

#include <iostream>
using namespace std;
void fun(int);
void fun(int&);
int main()
{
    int a = 10;
    fun(a); // error, which fun()?
    return 0;
}
void fun(int x) { cout << "Value of x is : " << x << endl; }
void fun(int& b)
{
    cout << "Value of b is : " << b << endl;
}
// Code Submitted By Susobhan Akhuli