#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);
}

打印:32333445