/*-------------------------------------------------------------------------*/
/* mystring.c                                                              */
/*-------------------------------------------------------------------------*/

#include "mystring.h"

size_t mystrlen(const char *pc)
{
   const char *pcStart = pc;
   while (*pc != '\0')
      ++pc;
   return pc - pcStart;
}

int mystrcmp(const char *pcFirst, const char *pcSecond)
{
   while ((*pcFirst != '\0') && (*pcFirst == *pcSecond))
   {
      ++pcFirst;
      ++pcSecond;
   }
    return *pcFirst - *pcSecond;
}

int mystrncmp(const char *pcFirst, const char *pcSecond, size_t uiCount)
{
   while ((uiCount > 0) && (*pcFirst != '\0') && (*pcFirst == *pcSecond))
   {
      ++pcFirst;
      ++pcSecond;
      --uiCount;
   }
   if (uiCount <= 0)
      return 0;
   return *pcFirst - *pcSecond;
}

char *mystrcpy(char *pcTo, const char *pcFrom)
{
    char *pcReturn = pcTo;
    while (*pcFrom != '\0')
    {
       *pcTo = *pcFrom;
       ++pcFrom;
       ++pcTo;
    }
    *pcTo = '\0';
    return pcReturn;
}

char *mystrncpy(char *pcTo, const char *pcFrom, size_t uiCount)
{
    char *pcReturn = pcTo;
    while (uiCount > 0)
    {
      *pcTo = *pcFrom;
      ++pcTo;
      if (*pcFrom != '\0')
         ++pcFrom;
      --uiCount;
    }
    return pcReturn;
}

char *mystrcat(char *pcTo, const char *pcFrom)
{
    char *pcReturn = pcTo;
    while (*pcTo != '\0')
      ++pcTo;
    while (*pcFrom != '\0')
    {
       *pcTo = *pcFrom;
       ++pcTo;
       ++pcFrom;
    }
    *pcTo = '\0';
    return pcReturn;
}

char *mystrncat(char *pcTo, const char *pcFrom, size_t uiCount)
{
    char *pcReturn = pcTo;
    while (*pcTo != '\0')
      ++pcTo;
    while ((uiCount > 0) && (*pcFrom != '\0'))
    {
       *pcTo = *pcFrom;
       ++pcTo;
       ++pcFrom;
        --uiCount;
    }
   *pcTo = '\0';
    return pcReturn;
}

char *mystrchr(const char *pc, int iChar)
{
   while (*pc != '\0')
   {
      if (*pc == (char)iChar)
         return (char*)pc;
      ++pc;
   }
   return NULL;
}

char *mystrrchr(const char *pc, int iChar)
{
   const char *pcReturn = NULL;
   while (*pc != '\0')
   {
      if (*pc == (char)iChar)
         pcReturn = pc;
      ++pc;
   }
   return (char*)pcReturn;
}
   
size_t mystrspn(const char *pc, const char *pcPrefixChars)
{
   const char *pcStart = pc;
   while ((*pc != '\0') && mystrchr(pcPrefixChars, *pc))
      ++pc;
   return pc - pcStart;
}

size_t mystrcspn(const char *pc, const char *pcPrefixChars)
{
   const char *pcStart = pc;
   while ((*pc != '\0') && ! mystrchr(pcPrefixChars, *pc))
      ++pc;
   return pc - pcStart;
}

char *mystrpbrk(const char *pc, const char *pcSearchChars)
{
   while (*pc != '\0')
   {
      if (mystrchr(pcSearchChars, *pc))
         return (char*)pc;
      ++pc;
   }
   return NULL;
}

static int strprefix(const char *pcSearchStr, const char *pc)
{
   while ((*pcSearchStr != '\0') && (*pcSearchStr == *pc))
   {
      ++pcSearchStr;
      ++pc;
   }
   if (*pcSearchStr != '\0')
      return 0;
   return 1;
}

char *mystrstr(const char *pc, const char *pcSearchStr)
{
   if (*pcSearchStr == '\0')
      return (char*)pc;

   while (*pc != '\0')
   {
      if (strprefix(pcSearchStr, pc))
         return (char*)pc;
      ++pc;
   }
   return NULL;
}