自己实现函数itoa()和strrev()

//itoa()将数字按给定的进制转变成字符串

//strrev()实现字符串翻转

/*************
*author :vinco zhang
*e-mail: [email protected]
*concentrate on both hardware and software of Embeded OS

* date:2011-01-03

*all right reserved
************/

#include<stdio.h>
#include<stdlib.h>
#include <string.h>
char* strrev(char* src,char* dst);
char* itoa(unsigned long n,char* str,int base);

int main(void)
{
 char src[11];//="zhangxuyun";
 int num=1234;
 itoa(num,src,10);
 //printf("itoa(),before the strrev():/nstr[]=%s,strlen(str)=%d/n",src,strlen(src));
 //strrev(src,dst);
 printf("num=%d,src=%s,strlen(src)=%d/n",num,src,strlen(src));

 return 0;
}
char* itoa(unsigned long n,char* str,int base)
{
 char* q=str;int m=n,r;//n=1234=0x4d2
 char tmp[15];
 char* p=tmp;
 while(m)
 {
 r=m%base;//r=1234%16=2  77%16=13=d  4%16=4; 
 m=m/base;//m=1234/16=77 77/16=4;
 if(r>=10) {r=r-10;*(p++)=r+'a';}
 else *(p++)=r+'0';
 }
 *(p++)='/0';
 strrev(tmp,q);
 //printf("str=%s,strlen(str)=%d/n",q,strlen(q));
 return q;
}
char* strrev(char* src,char* dst)
{
 int len=strlen(src);
 char* p=src+len-1;
 char* q=dst;
 while(len--) *(q++)=*(p--);
 *(q++)='/0';
 return dst;
}