в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:29:00Z

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==define macro==

<source lang="cpp">#define DemoVersion
#define PC 5
#include <iostream>

int main()
{
std::cout << "Checking on the definitions of DemoVersion,PC and MAC...\n";

#ifdef DemoVersion
std::cout << "DemoVersion defined.\n";
#else // DemoVersion
std::cout << "DemoVersion not defined.\n";
#endif // DemoVersion

#ifndef PC
std::cout << "PC not defined!\n";
#else // PC
std::cout << "PC defined as: " << PC << std::endl;
#endif // PC

#ifdef MAC
std::cout << "MAC defined!\n";
#else // MAC
std::cout << "MAC was not defined.\n";
#endif // MAC

std::cout << "Done.\n";
return 0;
}</source>
<pre class=codeResult>Checking on the definitions of DemoVersion,PC and MAC...
DemoVersion defined.
PC defined as: 5
MAC was not defined.
Done.</pre>

==Using #undef.==

<source lang="cpp">#define DemoVersion
#define DOS_VERSION 5
#include <iostream>
using namespace std;
int main()
{
#ifdef DemoVersion
cout << "DemoVersion defined.\n";
#else
cout << "DemoVersion not defined.\n";
#endif
#ifndef DOS_VERSION
cout << "DOS_VERSION not defined!\n";
#else
cout << "DOS_VERSION defined as: " << DOS_VERSION << endl;
#endif
#ifdef WINDOWS_VERSION
cout << "WINDOWS_VERSION defined!\n";
#else
cout << "WINDOWS_VERSION was not defined.\n";
#endif
#undef DOS_VERSION
#ifdef DemoVersion
cout << "DemoVersion defined.\n";
#else
cout << "DemoVersion not defined.\n";
#endif
#ifndef DOS_VERSION
cout << "DOS_VERSION not defined!\n";
#else
cout << "DOS_VERSION defined as: " << DOS_VERSION << endl;
#endif
#ifndef WINDOWS_VERSION
cout << "WINDOWS_VERSION defined!\n";
#else
cout << "WINDOWS_VERSION was not defined.\n";
#endif
cout << "Done.\n";
return 0;
}</source>

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в 14:21, 25 мая 2010

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