c语言String的实现

/*
 * String.c
 *
 *  Created on: 2012-12-4
 *      Author: Administrator
 */
#include <stdio.h>
#include <stdlib.h>
#define TRUE 1
#define FALSE 0
#define CHECK(t) do{if(!(t))return 0;}while(0)
typedef char* String;
typedef int Status;
static String STRBUFFER = 0;
int StrLen(String buf){
 String temp = buf;
 while(*temp++);
 return temp-buf-1;
}
String StrMake(int length){
 return (String)malloc(length+1);
}
String StrChr(String buf, char ch, int length){
 while(length--&&*buf++ != ch);
 return buf-1;
}
void StrCat(String *dest,String src){
 String temp = (String)malloc(StrLen(*dest)+StrLen(src)+1);
 String head = temp;
 String d = *dest;
 while(*d){
  *temp++ = *d++;
 }
 while(*src){
  *temp++ = *src++;
 };
 *temp = '\0';
 *dest = head;
}
int StrCmp(String buf1,String buf2){
 do{
  if(*buf1>*buf2)return 1;
  if(*buf1<*buf2)return -1;
  if(!*buf1)break;
  buf1++;
  buf2++;
 }while(1);
 return 0;
}
void StrCpy(String *dest,String src){
 *dest = StrMake(StrLen(src));
 String temp = *dest;
 while(*src){
  *temp++=*src++;
 }
 *temp = 0;
}
void StrFree(String *str){
 free(*str);
 *str = 0;
}

Status StrPrint(String str){
 CHECK(str);
 puts(str);
 return TRUE;
}
String StrTok(String dest,String src){
 if(dest)StrCpy(&STRBUFFER,dest);
 CHECK(src&&STRBUFFER&&*STRBUFFER);
 int length = StrLen(src);
 String ch = StrChr(src, *STRBUFFER, length);
 if(*ch == *STRBUFFER){
  do{
   *STRBUFFER++='\0';
   CHECK(*STRBUFFER);
   ch = StrChr(src, *STRBUFFER, length);
  }while(*ch == *STRBUFFER);
 }
 String result = STRBUFFER;
 String temp = result;
 while(*temp) {
  ch = StrChr(src, *temp, length);
  if (*ch == *temp) {
   *temp++ = '\0';
   CHECK(*temp);
   break;
  }else{
   temp++;
  }
 }
 STRBUFFER = temp;
 return result && *result ? result : 0;
}
String StrStr(String dest,String src){
 CHECK(dest&&src&&*dest&&*src);
 do{
  String temp = src,rt = dest;
  while(*temp == *rt){
   temp++;rt++;
  }
  if(!*temp)return dest;
  CHECK(*rt);
  dest++;
 }while(*dest);
 return 0;
}