Question

I am on a low level embedded system comparing a fixed size buffer of chars to a simple string. The buffer is much larger than the string so I think that that is why the comparison operators says that the two are not equal. This prompted me to write a simple function to compare the string to the beginning of the buffer – is this an elegant solution? Thanks

int CompareString(const char* string, int strlen)
{
     //first check to see if the length is the same
     //if there is a null char at string length then
     //they are equal
     if(MsgBuffer[strlen] != '\0')
     {
         return 0; //they are not equal
     }

     strlen = strlen - 1;

     while(strlen > -1)
     {
         if(string[strlen] != MsgBuffer[strlen])
         {
              return 0; //they are equal
         }

         strlen = strlen - 1;
     }

     return 1; //they are equal
}

Answer 1

Here is some code you can use. Simply pass the comparison string and the buffer as two parameters. This code should also be fully compliant with MISRA-C:2004.

sint8 gpfunc_strcmp (const uint8* s1, const uint8* s2)
{

  while ((*s1 != '\0') && (*s2 != '\0'))
  {
    if (*s1 != *s2)
    {
      break;
    }
    else
    {
      s1++; 
      s2++;
    }
  }

  return (sint8)(*s1 - *s2);
}