字符串操作

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1.是否存在字串的实现

bool IsExist(char *source, char *dest)
{
     assert((NULL != source) && (NULL != dest));
    if (strlen(source) < strlen(dest))
    {
          return false;
      }
      while (strlen(source) >= strlen(dest))
      {
       if (0 == strncmp(source, dest, strlen(dest)))
       {

          return true;
       }
       ++source;

}
return false;
}

2.字串个数

size_t GetSubNum(char *source, char *dest)
{
     size_t count = 0;
    assert((NULL != source) && (NULL != dest));
     while (strlen(source) >= strlen(dest))
    {
         if (0 == strncmp(source, dest, strlen(dest)))
       {
            ++count;
       }
        ++source;
    }
    return count;
}

3.判断字符串大小

#define GREATER_THAN 1 //大于
#define EQUAL 0 //等于
#define LESS_THAN -1 //小于

size_t bStrCmp(char *source, char *dest)
{
      assert((NULL != source) && (NULL != dest));
     while((*source != '\0') && (*dest != '\0'))
     {
           if (*source > *dest)
          {
              return GREATER_THAN;
           }
          if (*source < *dest)
         {
              return LESS_THAN;
         }
          ++source;
         ++dest;
     }
      if (*source != '\0')
     {
         return GREATER_THAN;
     }
     if (*dest != '\0')
     {
         return LESS_THAN;
      }
      return EQUAL;
}