十六进制数组转换成ASCII码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#define HEX2ASC(a)  ((((a)&0xF)>9)?((a)&0xF)-10+'a':((a)&0xF)+'0')
static void char_array_2_ascii(char *src,size_t src_len,char *str,size_t str_size){
  size_t i;
  if(str_size < 2*src_len+1)return;
  for(i=0;i<src_len;i++){
  *(str+2*i)=HEX2ASC(*(src+i)>>4);
  *(str+2*i+1)=HEX2ASC(*(src+i)&0xF);
  }
  *(str+2*i)='\0';
}
int main()
{
  unsigned char buf[]={0x32,0x33,0x34,0x45};
  char string[50];
  char_array_2_ascii((char *)buf,sizeof(buf),string,50);
  printf("%s\r\n",string);
}