macrosideeffects.cpp

ThinkingC++中文版

    //: C09:MacroSideEffects.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
#include "../require.h"
#include <iostream>
using namespace std;

//宏在C中有许多不安全的地方。如在此处经过C 预处理宏扩展之后，
//a++计算两次
//结果不是预期的。
#define BAND(x) (((x)>5 && (x)<10) ? (x) : 0)

void   main() {
//  ofstream out("macro.out");
//  assure(out, "macro.out");
  for(int i = 4; i < 11; i++) {
    int a = i;
    cout << "a = " << a << endl << '\t';
    cout << "BAND(++a)=" << BAND(++a) << endl;
    cout << "\t a = " << a << endl;
  }
} ///:~