C字符串操作函数实现方法小结

#ifndef NULL#define NULL ((void *)0)#endif/*  memcpy的实现代码*/void* memcpy(void *pDst, void *pSrc, int iLen){  char *pTmp = (char *)pDst;  char *pTmp2 = (char *)pSrc;  if(0 == iLen)    return pDst;  while(iLen--)    *pTmp++ = *pTmp2++;  return pDst;}/*  memset的实现代码*/void* memset(void *pDst, int iSet, int iLen){  char *pTmp = (char *)pDst;  if(0 == iLen)    return pDst;  while(iLen--)    *pTmp++ = (char)iSet;  return pDst;}/*  strcpy的实现代码*/char *strcpy(char *pDst, char *pSrc){  char *pRst = pDst;  do    *pDst++ = *pSrc;  while(*pSrc++);  return pRst;}/*  strcat的实现代码*/char *strcat(char *s, char *a){  char *save = s;  for(; *s; ++s);  while((*s++ = *a++) != 0);  return save;}/*  strlen的实现代码*/int strlen(char *pStr){  int iLen = 0;  while(*pStr++)    iLen++;  return iLen;}/*  strcmp的实现*/int strcmp(char *s, char *t){  for(; *s == *t; s++, t++)  {    if(('/0' == *s) || ('/0' == *t))    {      if(*s == *t)        return 0;      else        break;    }  }  return ((*s > *t) ? 1 : -1);}/*  strncmp的实现*/int m_strncmp(char *s, char *t, int n){  if(0 == n)    return 0;  for (; (--n > 0) && (*s==*t); s++,t++)  {    if ('/0'==*s)      return 0;  }  if(*s == *t)    return 0;  return ((*s > *t) ? 1 : -1);}/*  strstr的实现*/char* strstr(char *s, char *find){  char c, sc;  unsigned int len;  if ((c = *find++) != 0)   {    len = lzs_strlen(find);    do     {      do       {        if ((sc = *s++) == 0)          return (NULL);      } while (sc != c);    } while (lzs_strncmp(s, find, len) != 0);    s--;  }  return ((char *)s);}