编程语言及工具
写好C语言,漂亮的宏定义很重要,使用宏定义可以防止出错,提高可移植性,可读性,方便性等等。下面列举一些成熟软件中常用的宏定义。
1#ifndefCOMDEF_H2#defineCOMDEF_H3//头文件内容4#endif
1typedefunsignedcharboolean;/* Boolean value type. */2typedefunsignedlongintuint32;/* Unsigned 32 bit value */3typedefunsignedshortuint16;/* Unsigned 16 bit value */4typedefunsignedcharuint8;/* Unsigned 8 bit value */5typedefsignedlongintint32;/* Signed 32 bit value */6typedefsignedshortint16;/* Signed 16 bit value */7typedefsignedcharint8;/* Signed 8 bit value */
下面的不建议使用
1typedefunsignedcharbyte;/* Unsigned 8 bit value type. */2typedefunsignedshortword;/* Unsinged 16 bit value type. */3typedefunsignedlongdword;/* Unsigned 32 bit value type. */4typedefunsignedcharuint1;/* Unsigned 8 bit value type. */5typedefunsignedshortuint2;/* Unsigned 16 bit value type. */6typedefunsignedlonguint4;/* Unsigned 32 bit value type. */7typedefsignedcharint1;/* Signed 8 bit value type. */8typedefsignedshortint2;/* Signed 16 bit value type. */9typedeflongintint4;/* Signed 32 bit value type. */10typedefsignedlongsint31;/* Signed 32 bit value */11typedefsignedshortsint15;/* Signed 16 bit value */12typedefsignedcharsint7;/* Signed 8 bit value */
1#defineMEM_B( x ) ( *( (byte *) (x) ) )2#defineMEM_W( x ) ( *( (word *) (x) ) )
1#defineMAX( x, y ) ( ((x) > (y)) ? (x) : (y) )2#defineMIN( x, y ) ( ((x) < (y)) ? (x) : (y) )
1#defineFPOS( type, field )2/*lint -e545 */( (dword) &(( type *) 0)-> field )/*lint +e545 */
1#define FSIZ(type, field ) sizeof( ((type*) 0)->field )
1#defineFLIPW(ray) ( (((word) (ray)[0]) * 256) + (ray)[1])
1#define FLOPW( ray,val)2(ray)[0] = ((val) /256);3(ray)[1] = ((val) &0xFF)
1#define B_PTR(var) ( (byte *) (void*) &(var) )2#define W_PTR(var) ( (word *) (void*) &(var) )
1#defineWORD_LO(xxx) ((byte) ((word)(xxx) & 255))2#defineWORD_HI(xxx) ((byte) ((word)(xxx) >> 8))
1#defineRND8( x ) ((((x) + 7) / 8 ) * 8 )
1#defineUPCASE( c ) ( ((c) >='a'&& (c) <='z') ? ((c) - 0x20) : (c) )
1#defineDECCHK( c ) ((c) >='0'&& (c) <='9')
1#defineHEXCHK( c ) ( ((c) >='0'&& (c) <='9') ||2((c) >='A'&& (c) <='F') ||3((c) >='a'&& (c) <='f') )
1#define INC_SAT(val) (val= ((val)+1> (val)) ? (val)+1: (val))
1#define ARR_SIZE( a ) ( sizeof( (a) ) / sizeof( (a[0]) ) )
1#defineMOD_BY_POWER_OF_TWO( val, mod_by )2( (dword)(val) & (dword)((mod_by)-1) )
1#define inp(port)(*((volatile byte *)(port)))2#define inpw(port)(*((volatile word *)(port)))3#define inpdw(port)(*((volatile dword *)(port)))4#define outp(port, val)(*((volatile byte *)(port)) = ((byte) (val)))5#define outpw(port, val)(*((volatile word *)(port)) = ((word) (val)))6#define outpdw(port, val)(*((volatile dword *)(port)) = ((dword) (val)))
A N S I标准说明了五个预定义的宏名。它们是:
1_ L I N E _2_FI L E _3_ D ATE _4_TI M E _5_ STD C _
如果编译不是标准的,则可能仅支持以上宏名中的几个,或根本不支持。记住编译程序也许还提供其它预定义的宏名。
_ L I N E _
及_ F I L E _
宏指令在有关# l i n e
的部分中已讨论,这里讨论其余的宏名。
_ D AT E _
宏指令含有形式为月/日/年的串,表示源文件被翻译到代码时的日期。
源代码翻译到目标代码的时间作为串包含在_ T I M E _
中。串形式为时:分:秒。
如果实现是标准的,则宏_ S T D C _
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。
可以定义宏,例如: 当定义了_DEBUG
,输出数据信息和所在文件所在行
1#ifdef_DEBUG2#defineDEBUGMSG(msg,date) printf(msg);printf(“%d%d%d”,date,_LINE_,_FILE_)3#else4#defineDEBUGMSG(msg,date)5#endif
例如:
1#define ADD(a,b) (a+b)
用do{}while(0)
语句包含多语句防止错误
例如:
1#difne DO(a,b) a+b;2a++;
应用时:
1if(….)2DO(a,b);//产生错误3else
解决方法:
1#difneDO(a,b)do{a+b;2a++;}while(0)
审核编辑:汤梓红
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