ccsun1 testc > cat -n overload.cpp
     1	///
     2	/*** overload.cpp, CopyLeft by tsaiwn@csie.nctu.edu.tw  */
     3	/*** C, C++ 都可用 pass by value      ***/
     4	/*** C uses pass by address-to-pointer 才能改變參數! ***/
     5	/*** C++ 可以用 pass by reference 以改變參數        ***/
     6	/*** =========================================***/
     7	#include <iostream.h>
     8	  // 新版 C++ 可用 #include <iostream>    
     9	   /// 但同時也要記得寫 using namespace std;   
    10	void swapold();     // C++ 用到之前需要先宣告 !
    11	void swap(int&, int&);          // swap 整數 
    12	void swap(double&, double&);       // swap double 實數 
    13	
    14	int main()
    15	{
    16	    int m=3, n=8;
    17	    double x=250.75, y=333.625;
    18	    cout << "m=" << m << endl;
    19	    cout << "n=" << n << endl;
    20	    cout << "x=" << x << ",\t y=" << y << endl;
    21	
    22	///    swapold(&m, &n);     /*  C 與 C++ 都可這樣用 swapold */
    23	//
    24	    swap(m, n);    //  C++ 可以這樣用! 注意是 pass by reference 
    25	    cout << "After swap(m,n) --- m="<<m <<" , n=" << n << endl;
    26	    swap(x, y);
    27	        // 這次會用到參數是 double 的 swap(double&, double&)
    28	        /// 事實上, Compiler 是把函數名稱偷偷換掉成像 _swap_F2RdRd
    29	         ///-----------------------   ..    或是像 _swap_F2RiRi
    30	          /// 你可以用 g++ -S myfile.cpp 翻譯成 組語程式看看
    31	    cout << "After swap(x,y) --- x="<<x <<" , y=" << y << endl;
    32	}
    33	void swapold(int* pa, int*pb)
    34	{ int tmp;
    35	      tmp = *pa;
    36	      *pa = *pb;
    37	      *pb = tmp;
    38	}
    39	void swap(int &x, int&y)
    40	{ int tmp;
    41	      tmp = x;
    42	      x = y;
    43	      y = tmp;
    44	}
    45	void swap(double& x, double&y)
    46	{ double tmp;
    47	      tmp = x;
    48	      x = y;
    49	      y = tmp;
    50	}
ccsun1 testc > g++ overload.cpp
ccsun1 testc > ./a.out
m=3
n=8
x=250.75,	 y=333.625
After swap(m,n) --- m=8 , n=3
After swap(x,y) --- x=333.625 , y=250.75
ccsun1 testc > 
ccsun1 testc > g++ -S overload.cpp -Wno-deprecated
ccsun1 testc > grep swap overload.s | head -5
        .string "After swap(m,n) --- m="
        .string "After swap(x,y) --- x="
        call    _Z4swapRiS_
        call    _Z4swapRdS_
        .globl _Z7swapoldPiS_
ccsun1 testc >