help2.cpp

help2这个类是用C++写成的 非常有意思而且对初学者有帮助

/* 
   Project 3-2 
 
   An improved Help system that uses a 
   a do-while to process a menu selection. 
*/ 
 
#include <iostream> 
using namespace std; 
 
int main() { 
  char choice; 
 
  do { 
    cout << "Help on:\n"; 
    cout << "  1. if\n"; 
    cout << "  2. switch\n"; 
    cout << "  3. for\n"; 
    cout << "  4. while\n"; 
    cout << "  5. do-while\n"; 
    cout << "Choose one: "; 
 
    cin >> choice; 
 
  } while( choice < '1' || choice > '5'); 
 
  cout << "\n\n"; 
  
  switch(choice) { 
    case '1': 
      cout << "The if:\n\n"; 
      cout << "if(condition) statement;\n"; 
      cout << "else statement;\n"; 
      break; 
    case '2': 
      cout << "The switch:\n\n"; 
      cout << "switch(expression) {\n"; 
      cout << "  case constant:\n"; 
      cout << "    statement sequence\n"; 
      cout << "    break;\n"; 
      cout << "  // ...\n"; 
      cout << "}\n"; 
      break; 
    case '3': 
      cout << "The for:\n\n"; 
      cout << "for(init; condition; iteration)"; 
      cout << " statement;\n"; 
      break; 
    case '4': 
      cout << "The while:\n\n"; 
      cout << "while(condition) statement;\n"; 
      break; 
    case '5': 
      cout << "The do-while:\n\n"; 
      cout << "do {\n"; 
      cout << "  statement;\n"; 
      cout << "} while (condition);\n"; 
      break; 
  } 
 
  return 0; 
}