//sortSTL.cpp  -- Demo using sort( ) in C++ STL Library
// @CopyLeft by tsaiwn@cs.nctu.edu.tw; 這個程式是 C++ 程式, 必須用 g++
// 站在巨人肩膀上: 使用女共匪寫的 C++ STL 程式庫的 sort( )
#include <iostream>
#include <algorithm>
using namespace std;  // 規定要這樣才可用 C++ 程式庫 std::
int x[ ] = {38, 49, 88, 58, 38, 77, 66, 68, 55, 95, 88, 65};
const int NX = (sizeof x / sizeof x[0]);
double y[ ]={55, 68.5, 66.6, 78.5, 38, 49, 38, 88, 58};
const int NY = (sizeof y / sizeof y[0]);
template <class T> void print(T a, int n) {
    int i; cout << "  "<< a[0];    // cout 就是螢幕
    for(i=1; i < n; i++) {
        if(i%5 == 0) cout << endl<< "  "<<a[i];  // 每五個換下一列
        else cout << ",  " << a[i];
    } // for
    cout << endl;  // endl 就是 "\n" 啦!
}//print(
template<class GG>    // 注意這是樣板函數(template function)
  bool comp(const GG& a, const GG& b) { return b < a; } //遞減
int main( ) {
   char ggtmp[99];
   cout << "Before sort:\n";  print(x, NX);
   sort(x, x+NX);  // 由小到大, 自然序
   cout << " After sort:\n";  print(x, NX);
   cout << " Sort again with compare function comp:\n";
   sort(x, x+NX, comp<int>); print(x, NX);
   cout << "=== === ===\n";
   cout << "Before sort y:\n";  print(y, NY);
   sort(y, y+NY);  // 由小到大
   cout << " After sort:\n";  print(y, NY);
   cout << " Sort again with compare function comp():\n";
   sort(y, y+NY, comp<double>); print(y, NY);
   cout << "Hit any key and then ENTER key...";
   cin >> ggtmp;  //暫停!  cin 就是鍵盤, 注意要打至少一字後按 ENTER
   return 0;
}// main( 
/******   注意 compare function 是 bool 要回傳 true 或 false
D:\test> path C:\Dev-Cpp\bin;%path%

D:\test> g++ sortSTL.cpp

D:\test> a.exe
Before sort:
  38,  49,  88,  58,  38
  77,  66,  68,  55,  95
  88,  65
 After sort:
  38,  38,  49,  55,  58
  65,  66,  68,  77,  88
  88,  95
 Sort again with compare function comp:
  95,  88,  88,  77,  68
  66,  65,  58,  55,  49
  38,  38
=== === ===
Before sort y:
  55,  68.5,  66.6,  78.5,  38
  49,  38,  88,  58
 After sort:
  38,  38,  49,  55,  58
  66.6,  68.5,  78.5,  88
 Sort again with compare function comp():
  88,  78.5,  68.5,  66.6,  58
  55,  49,  38,  38
Hit any key and then ENTER key...bye
D:\test> 
*** === 看完這有沒有發現 C++ 寫這麼短的程式就能做這麼多事? ******/