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    外部函数

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    外部函数

    一、外部函数

    主函数(files.c)

    #include <stdio.h>
main()
{int a,b;printf("a=");scanf("%d",&a);printf("b=");scanf("%d",&b);printf("\n");add(a,b);printf("\n");sub(a,b);}

    外部函数(file1.c)

    #include <stdio.h>
extern add(int c,int d)  // extern 声明外部函数  可省略
{
printf("%d+%d=%d\n",c,d,c+d);
}

    外部函数(file2.c)

    #include <stdio.h>
extern sub(int c,int d)
{
printf("%d-%d=%d\n",c,d,c-d);
}

    二、.h文件与.c文件

    reg52.h

    /*--------------------------------------------------------------------------
REG52.HHeader file for generic 80C52 and 80C32 microcontroller.
Copyright (c) 1988-2002 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.
--------------------------------------------------------------------------*/#ifndef __REG52_H__
#define __REG52_H__/*  BYTE Registers  */
sfr P0    = 0x80;
sfr P1    = 0x90;
sfr P2    = 0xA0;
sfr P3    = 0xB0;
sfr PSW   = 0xD0;
sfr ACC   = 0xE0;
sfr B     = 0xF0;
sfr SP    = 0x81;
sfr DPL   = 0x82;
sfr DPH   = 0x83;
sfr PCON  = 0x87;
sfr TCON  = 0x88;
sfr TMOD  = 0x89;
sfr TL0   = 0x8A;
sfr TL1   = 0x8B;
sfr TH0   = 0x8C;
sfr TH1   = 0x8D;
sfr IE    = 0xA8;
sfr IP    = 0xB8;
sfr SCON  = 0x98;
sfr SBUF  = 0x99;/*  8052 Extensions  */
sfr T2CON  = 0xC8;
sfr RCAP2L = 0xCA;
sfr RCAP2H = 0xCB;
sfr TL2    = 0xCC;
sfr TH2    = 0xCD;/*  BIT Registers  */
/*  PSW  */
sbit CY    = PSW^7;
sbit AC    = PSW^6;
sbit F0    = PSW^5;
sbit RS1   = PSW^4;
sbit RS0   = PSW^3;
sbit OV    = PSW^2;
sbit P     = PSW^0; //8052 only/*  TCON  */
sbit TF1   = TCON^7;
sbit TR1   = TCON^6;
sbit TF0   = TCON^5;
sbit TR0   = TCON^4;
sbit IE1   = TCON^3;
sbit IT1   = TCON^2;
sbit IE0   = TCON^1;
sbit IT0   = TCON^0;/*  IE  */
sbit EA    = IE^7;
sbit ET2   = IE^5; //8052 only
sbit ES    = IE^4;
sbit ET1   = IE^3;
sbit EX1   = IE^2;
sbit ET0   = IE^1;
sbit EX0   = IE^0;/*  IP  */
sbit PT2   = IP^5;
sbit PS    = IP^4;
sbit PT1   = IP^3;
sbit PX1   = IP^2;
sbit PT0   = IP^1;
sbit PX0   = IP^0;/*  P3  */
sbit RD    = P3^7;
sbit WR    = P3^6;
sbit T1    = P3^5;
sbit T0    = P3^4;
sbit INT1  = P3^3;
sbit INT0  = P3^2;
sbit TXD   = P3^1;
sbit RXD   = P3^0;/*  SCON  */
sbit SM0   = SCON^7;
sbit SM1   = SCON^6;
sbit SM2   = SCON^5;
sbit REN   = SCON^4;
sbit TB8   = SCON^3;
sbit RB8   = SCON^2;
sbit TI    = SCON^1;
sbit RI    = SCON^0;/*  P1  */
sbit T2EX  = P1^1; // 8052 only
sbit T2    = P1^0; // 8052 only/*  T2CON  */
sbit TF2    = T2CON^7;
sbit EXF2   = T2CON^6;
sbit RCLK   = T2CON^5;
sbit TCLK   = T2CON^4;
sbit EXEN2  = T2CON^3;
sbit TR2    = T2CON^2;
sbit C_T2   = T2CON^1;
sbit CP_RL2 = T2CON^0;#endif

     

    // 下列结构的作用：防止不同.h文件中的声明相互冲突   
#ifndef __REG52_H__  // __REG52_H__  标识符 唯一   .c文件中引用#include<reg52.h>
#define __REG52_H__#endif               // 结束标志

    intrins.h文件

    /*--------------------------------------------------------------------------
INTRINS.HIntrinsic functions for C51.
Copyright (c) 1988-2004 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.
--------------------------------------------------------------------------*/#ifndef __INTRINS_H__
#define __INTRINS_H__extern void          _nop_     (void);
extern bit           _testbit_ (bit);
extern unsigned char _cror_    (unsigned char, unsigned char);
extern unsigned int  _iror_    (unsigned int,  unsigned char);
extern unsigned long _lror_    (unsigned long, unsigned char);
extern unsigned char _crol_    (unsigned char, unsigned char);
extern unsigned int  _irol_    (unsigned int,  unsigned char);
extern unsigned long _lrol_    (unsigned long, unsigned char);
extern unsigned char _chkfloat_(float);
extern void          _push_    (unsigned char _sfr);
extern void          _pop_     (unsigned char _sfr);#endif

    .h文件中只声明变量

    .c文件与.h文件的注意事项

     1、模块即是一个.c文件和一个.h文件的结合，头文件(.h)中是对于该模块接口的声明；

     2、某模块提供给其它模块调用的外部函数及数据需在.h中文件中冠以extern关键字声明；

     3、模块内的函数和全局变量需在.c文件开头冠以static关键字声明；

     4、永远不要在.h文件中定义变量！定义变量和声明变量的区别在于定义会产生内存分配的操作，是汇编阶段的概念；

    外部函数

    一、外部函数

    主函数(files.c)

    #include <stdio.h>
main()
{int a,b;printf("a=");scanf("%d",&a);printf("b=");scanf("%d",&b);printf("\n");add(a,b);printf("\n");sub(a,b);}

    外部函数(file1.c)

    #include <stdio.h>
extern add(int c,int d)  // extern 声明外部函数  可省略
{
printf("%d+%d=%d\n",c,d,c+d);
}

    外部函数(file2.c)

    #include <stdio.h>
extern sub(int c,int d)
{
printf("%d-%d=%d\n",c,d,c-d);
}

    二、.h文件与.c文件

    reg52.h

    /*--------------------------------------------------------------------------
REG52.HHeader file for generic 80C52 and 80C32 microcontroller.
Copyright (c) 1988-2002 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.
--------------------------------------------------------------------------*/#ifndef __REG52_H__
#define __REG52_H__/*  BYTE Registers  */
sfr P0    = 0x80;
sfr P1    = 0x90;
sfr P2    = 0xA0;
sfr P3    = 0xB0;
sfr PSW   = 0xD0;
sfr ACC   = 0xE0;
sfr B     = 0xF0;
sfr SP    = 0x81;
sfr DPL   = 0x82;
sfr DPH   = 0x83;
sfr PCON  = 0x87;
sfr TCON  = 0x88;
sfr TMOD  = 0x89;
sfr TL0   = 0x8A;
sfr TL1   = 0x8B;
sfr TH0   = 0x8C;
sfr TH1   = 0x8D;
sfr IE    = 0xA8;
sfr IP    = 0xB8;
sfr SCON  = 0x98;
sfr SBUF  = 0x99;/*  8052 Extensions  */
sfr T2CON  = 0xC8;
sfr RCAP2L = 0xCA;
sfr RCAP2H = 0xCB;
sfr TL2    = 0xCC;
sfr TH2    = 0xCD;/*  BIT Registers  */
/*  PSW  */
sbit CY    = PSW^7;
sbit AC    = PSW^6;
sbit F0    = PSW^5;
sbit RS1   = PSW^4;
sbit RS0   = PSW^3;
sbit OV    = PSW^2;
sbit P     = PSW^0; //8052 only/*  TCON  */
sbit TF1   = TCON^7;
sbit TR1   = TCON^6;
sbit TF0   = TCON^5;
sbit TR0   = TCON^4;
sbit IE1   = TCON^3;
sbit IT1   = TCON^2;
sbit IE0   = TCON^1;
sbit IT0   = TCON^0;/*  IE  */
sbit EA    = IE^7;
sbit ET2   = IE^5; //8052 only
sbit ES    = IE^4;
sbit ET1   = IE^3;
sbit EX1   = IE^2;
sbit ET0   = IE^1;
sbit EX0   = IE^0;/*  IP  */
sbit PT2   = IP^5;
sbit PS    = IP^4;
sbit PT1   = IP^3;
sbit PX1   = IP^2;
sbit PT0   = IP^1;
sbit PX0   = IP^0;/*  P3  */
sbit RD    = P3^7;
sbit WR    = P3^6;
sbit T1    = P3^5;
sbit T0    = P3^4;
sbit INT1  = P3^3;
sbit INT0  = P3^2;
sbit TXD   = P3^1;
sbit RXD   = P3^0;/*  SCON  */
sbit SM0   = SCON^7;
sbit SM1   = SCON^6;
sbit SM2   = SCON^5;
sbit REN   = SCON^4;
sbit TB8   = SCON^3;
sbit RB8   = SCON^2;
sbit TI    = SCON^1;
sbit RI    = SCON^0;/*  P1  */
sbit T2EX  = P1^1; // 8052 only
sbit T2    = P1^0; // 8052 only/*  T2CON  */
sbit TF2    = T2CON^7;
sbit EXF2   = T2CON^6;
sbit RCLK   = T2CON^5;
sbit TCLK   = T2CON^4;
sbit EXEN2  = T2CON^3;
sbit TR2    = T2CON^2;
sbit C_T2   = T2CON^1;
sbit CP_RL2 = T2CON^0;#endif

     

    // 下列结构的作用：防止不同.h文件中的声明相互冲突   
#ifndef __REG52_H__  // __REG52_H__  标识符 唯一   .c文件中引用#include<reg52.h>
#define __REG52_H__#endif               // 结束标志

    intrins.h文件

    /*--------------------------------------------------------------------------
INTRINS.HIntrinsic functions for C51.
Copyright (c) 1988-2004 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.
--------------------------------------------------------------------------*/#ifndef __INTRINS_H__
#define __INTRINS_H__extern void          _nop_     (void);
extern bit           _testbit_ (bit);
extern unsigned char _cror_    (unsigned char, unsigned char);
extern unsigned int  _iror_    (unsigned int,  unsigned char);
extern unsigned long _lror_    (unsigned long, unsigned char);
extern unsigned char _crol_    (unsigned char, unsigned char);
extern unsigned int  _irol_    (unsigned int,  unsigned char);
extern unsigned long _lrol_    (unsigned long, unsigned char);
extern unsigned char _chkfloat_(float);
extern void          _push_    (unsigned char _sfr);
extern void          _pop_     (unsigned char _sfr);#endif

    .h文件中只声明变量

    .c文件与.h文件的注意事项

     1、模块即是一个.c文件和一个.h文件的结合，头文件(.h)中是对于该模块接口的声明；

     2、某模块提供给其它模块调用的外部函数及数据需在.h中文件中冠以extern关键字声明；

     3、模块内的函数和全局变量需在.c文件开头冠以static关键字声明；

     4、永远不要在.h文件中定义变量！定义变量和声明变量的区别在于定义会产生内存分配的操作，是汇编阶段的概念；

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