#define代码集合

/**
 *  文  件：Definesing.cpp
 *  功  能：宏定义的实例集合！
 *  作  者：rainy_blue_sky
 *  主  页：http://hi.baidu.com/rainy_blue_sky
 *  说  明：请尊重知识产权，转载请勿删掉该注释！
 */
#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;


int main()
{
    //ofstream cout("1.txt");

    cout << "******特殊的define用法******\n";
    #define A1(a) T_##a     //A1(1) --> T_1
    #define A2(a) @a        //A2(1) --> '1'
    #define A3(a) #a        //A3(1) --> "1"
    #define T_1 10
    cout << A1(1) << endl;
//    cout << A2(1) << endl;        //无法编译通过
    cout << A3(1) << endl;

    cout << "\n******define的多行定义******\n";
    #define MACRO(arg1, arg2) do{\
    /*declarations*/\
    int a;\
    int b;\
    a = arg1;\
    b = arg2;\
    cout << a << "\t" << b << endl;\
    /*other statement*/\
    }while(0)
    MACRO(10, 20);

    cout << "\n******如何定义宏、取消宏******\n";
    #define PI (3.1415926)
    #undef PI
    cout << "#define [MacroName] [MacroValue]\n"
         << "#unde [MacroName]\n";

    cout << "\n******条件编译******\n";
    #ifdef SJ
    cout << "SJ is Define" << endl;
    #else
    cout << "SJ is not Define" << endl;
    #endif // SJ

    cout << "\n******重新定义类型******\n";
    typedef unsigned char boolean;
    typedef unsigned long int uint32;
    typedef unsigned short uint16;
    typedef unsigned char uint8;
    typedef signed long int int32;
    typedef signed short int16;
    typedef signed char int8;
    cout << "typedef unsigned char boolean;\n"
         << "typedef unsigned long int uint32;\n"
         << "typedef unsigned short uint16;\n"
         << "typedef unsigned char uint8;\n"
         << "typedef signed long int int32;\n"
         << "typedef signed short int16;\n"
         << "typedef signed char int8;\n";
    unsigned char a;
    a = 'c';

    cout << "\n******得到指定地址上的一个字节或者字******\n";
    typedef unsigned char byte;
    typedef unsigned short word;
    #define GET_BYTE(x) (*((byte*)(x)))
    #define GET_WORD(x) (*((word*)(x)))
    int address = 0;
    setiosflags(ios::uppercase);
    cout << GET_BYTE(&a) << endl
         << GET_WORD(&a) << endl;

    cout << "\n******得到一个field在结构体(struct)中的偏移量******\n";
    #define FPOS(type, field) ((int)&(((type*)0)->field))
    struct SizeOfStruct
    {
        unsigned int s1;
        char s2;
        unsigned int s3;
        unsigned int s4;
    };
    cout << "SizeOfStruct: " << sizeof(SizeOfStruct) << endl;
    cout << "s1: " << FPOS(SizeOfStruct, s1) << endl;
    cout << "s2: " << FPOS(SizeOfStruct, s2) << endl;
    cout << "s3: " << FPOS(SizeOfStruct, s3) << endl;
    cout << "s4: " << FPOS(SizeOfStruct, s4) << endl;

    cout << "\n******得到一个field在结构体(struct)中的所占的偏移量******\n";
    #define FSIZE(type, field) sizeof(((type*)0)->field)
    cout << "SizeOfStruct: " << sizeof(SizeOfStruct) << endl;
    cout << "s1: " << FSIZE(SizeOfStruct, s1) << endl;
    cout << "s2: " << FSIZE(SizeOfStruct, s2) << endl;
    cout << "s3: " << FSIZE(SizeOfStruct, s3) << endl;
    cout << "s4: " << FSIZE(SizeOfStruct, s4) << endl;

    cout << "\n******按照LSB格式把两个直接转化为一个Word******\n";
    #define MERGE_BYTE(byte1, byte2) (((word)((byte1)*256))+ (byte2))
    byte mergeA = 0x10;
    byte mergeB = 0x20;
    cout << hex <<MERGE_BYTE(mergeA, mergeB) << endl;


    cout << "\n******按照LSB格式把WORD拆分为byte******\n";
    #define SEGMENTATION(com, byte1, byte2) {\
        byte1 = ((com)/256);\
        byte2 = ((com)&0xFF);\
    }
    word com = 0x1020;
    byte byte1, byte2;
    SEGMENTATION(com, byte1, byte2);
    cout << hex << (int)byte1 << "\t" << (int)byte2 << endl;

    cout << "\n******得到一个字的高位和低位字节******\n";
    #define WORD_LO(value) ((byte)((value)&0xFF))
    #define WORD_HI(value) ((byte)((value)>>8))
    word value = 0x1020;
    byte low, high;
    cout << hex << "value: " << value << endl
         << "low: " << (int)WORD_LO(value) << endl
         << "high: " << (int)WORD_HI(value) << endl;

    cout << "\n******返回一个比x大的8的倍数******\n";
    #define SEED8(x) ( ((x)+7)/8*8 )
    int seed1 = 11;
    cout << "x = 10: " << SEED8(seed1) << endl;

    cout << "\n******将字母转换为大写******\n";
    #define UPCASE(c) (((c) >= 0x61 && (c) <= 0x7A) ? ((c) - 0x20) : (c))
    cout << "a: " << (char)UPCASE('a') << endl;

    cout << "\n******变量自增防止溢出******\n";
    #define INC_VAL(val) ((val) = (((val)+1) > (val)) ? (val)+1 : (val))
    unsigned int valueInc = 0xFFFFFFFF;
    cout << "valueInc: " << valueInc << endl;
    cout << "INC_VAL(valueInc): " << INC_VAL(valueInc) << endl;

    cout << "\n******返回数组元素的个数******\n";
    #define ARR_SIZE(a) (sizeof((a))/sizeof((a)[0]))
    int ARR[20] = {0};
    cout << sizeof(ARR) << "\t" << sizeof(ARR[0]) << endl;
    cout << "ARR[20]: " << ARR_SIZE(ARR) << endl;

    cout << "\n******调试跟踪宏******\n";
    cout << "__LINE__: " << __LINE__ << endl
         << "__FILE__: " << __FILE__ << endl
         << "__DATE__: " << __DATE__ << endl
         << "__TIME__: " << __TIME__ << endl
         << "__STDC__: " << __STDC__ << endl;
    #ifdef _DEBUG
        cout << "hello: " << endl;
    #endif // __DEBUG
    int a12 = 10;
    a12 ++;

    cout << "\n******宏定义防止错误使用大括号包含******\n";
    #define BRACES_ERROR {cout << "BRACES ERROR!\n";}
    #define DOWHILE_RIGHT do{\
        cout << "DOWHILE RIGHT!\n";\
    }while(0)
/*    if(1) //去掉注释会出现错误
        BRACES_ERROR;
    else
    {
    }
*/
    if(1)
        DOWHILE_RIGHT;
    else
    {
    }

    return  0;
}

/**
 *  实例总结：
 *      特殊的define用法:
 *          通过使用其特殊的用法，可以控制代码，这是非常有用的，
 *          需要有一个意识，代码控制的是逻辑，所以宏定义是对代码进行的编程。
 *      define的多行定义:
 *          通过这种形式可以实现复杂的函数，不过宏定义的函数也有自己的弊端，在此从略。
 *      条件编译:
 *          条件编译的用处很多！其实，我们现在应该是更进一步的体会条件编译，
 *          编译器的控制。
 *      得到指定地址上的一个字节或者字:
 *          这是一种很简单的用法，就是将地址转换为指定的格式（这里可以理解格式的本质）
 *          之后，在对其进行取值！
 *      调试跟踪宏:
 *          __STDC__ 宏指令的意义是编译时定义的。一般来讲，如果__STDC__已经定义，
 *          编译器将仅接受不包含任何非标准扩展的标准C/C++代码。如果实现是标准的,
 *          则宏__STDC__含有十进制常量1。如果它含有任何其它数,则实现是非标准的。
 *      宏定义防止错误使用大括号包含:
 *          这是由于if语句固有的特性决定的if{};那么if语句结束，如果后面有else，也不会匹配！
 *
 */