ch5-3.c

单片机接口技术(C51版)例程源代码

/*程序功能：使用指针变量作函数调用的实参，升序输出2个整数*/
/******************************************************/
/*exchange()功能：交换2个形参指针变量所指向的变量的值  */
/*形参：2个，均为指向整型数据的指针变量                */
/*返回值：无                                           */
/******************************************************/
#include<stdio.h>
#include<reg51.h>
void exchange(int *pointer1, int *pointer2)
  { int temp;
    temp=*pointer1, *pointer1=*pointer2, *pointer2=temp;
  }
/*主函数main()*/
void main(void)
  { int num1,num2;
    int *num1_p=&num1, *num2_p=&num2; 	        /*定义并初始化指针变量num1_p和 num2_p */
    #ifndef MONITOR51
    SCON  = 0x50;		        /* SCON: mode 1, 8-bit UART, enable rcvr      */
    TMOD |= 0x20;               /* TMOD: timer 1, mode 2, 8-bit reload        */
    TH1   = 221;                /* TH1:  reload value for 1200 baud @ 16MHz   */
    TR1   = 1;                  /* TR1:  timer 1 run                          */
    TI    = 1;                  /* TI:   set TI to send first char of UART    */
    #endif
    printf("\n Input the first number: "); scanf("%d",num1_p);
    printf("\n Input the second number: "); scanf("%d",num2_p);
    printf("\n num1=%d, num2=%d ", num1, num2);	/*输出num1和num2的初始值*/
    if( *num1_p > *num2_p ) 		 	/* *num1_p > *num2_p (即num1>num2)*/
       exchange(num1_p, num2_p); 		/*指针变量作实参，调用exchange()函数*/
    printf("\n min=%d, max=%d\ ", num1, num2); 	/*输出排序后的num1和num2的值*/
    while(1);
  }