求解一个c语言问题， 把字符转换位相应的十六进制数, 并存入一个字节中

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

char atohex(char s)

{

char n = s

if( n >= 'a' &&n <= 'z')

n = n + 'A' - 'a'

if(n >源扒 0x39) //alpha

return (n - 0x37)

else //number

return (n - 0x30)

}

unsigned char chartohex(unsigned char *str)

{

unsigned char code[3]

unsigned char temp

memset(code, 0, 3)

memcpy(code, str, 2)

temp = atohex(code[0])

printf("the temp is %x\n", temp)

temp = (temp <<4) &0xF0

printf("the temp is %x\n", temp)

temp |= atohex(code[1])

printf("the code is %s\n", code)

/卜裂隐/printbinary(temp)

printf("the temp is %x, the sizeof(temp) is %d\n", temp, sizeof(temp))

return temp

}

int main()

{

unsigned char pstr[] = "aB"

unsigned char c, z

c = chartohex(pstr)

printf("The c hex is %x\n", c)

z = c

printf("The c dec is %d\型厅n", z)

return 0

}

#include"reg52.h"

#define uchar unsigned char

#define uint unsigned int

sbit BELL=P1^0//定义蜂鸣器

sbit key1=P1^1//定义按键

sbit key2=P1^2//定义按键

uint num

/*1ms廷时*/

void  delay_ms(uint z)

{

uint i,j

for(i=0i<zi++)

for(j=0j<110j++)

}

/*定时器初始化*/

void init_timer0()

{

TMOD=0x01

TH0=(65535-2000)/256

TL0=(65535-2000)%256

EA=0

ET0=1

TR0=1

}

void main()

{

BELL=0

init_timer0()

while(1)

{

    if(key1==0)

{

delay_ms(10)   穗乎镇      //延时消抖

if(key1==0)           //再次判断按键是否真的被按下

{

while(key1==0)   //等待释放按键

EA=1           //开启总中断

}

}

    if(key2==0)

{

delay_ms(10)         //延时消抖

if(key2==0)           //再次判断按键是否真的被按下

{

while(key2==0)   //等待释顷并放按键

EA=0     //关闭总中断

BELL=0      //关闭蜂鸣器

}

}

}

}

void timer0() interrupt 1

{

TH0=(65535-2000)/256

TL0=(65535-2000)%256         //中断计时2ms（500Hz），之所以猜粗用中断是因为定时比较准确 想改延时就把里面的2000改掉，这个数除以1000得的数就是多少毫秒

num++

if(num==1)                  //让蜂鸣器工以 500Hz频率工作

{

num=0

BELL=~BELL

}

}

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