C167 reading/scanning input from GSM module from RS232

Note also that your definitions of 'string' come after executable code - you can't do that in 'C'.

You can do it in C++, but not in 'C'.

Be sure that you're rading a 'C' textbook, not C++!

Note also that your definitions of 'string' come after executable code - you can't do that in 'C'.

You can do it in C++, but not in 'C'.

Be sure that you're rading a 'C' textbook, not C++!

Interfacing to GSM can be a pain. You may find the code below useful - I certainly did - it is a string compare function with a limited wildcard facility.

/*****************************************************************************
 *
 *  String Compare
 *
 *  Trigger:    Local call.
 *
 *  Input:      Pointers to the 'expected' and 'search' strings.
 *
 *  Output:     Returns TRUE to indicate a match and FALSE otherwise.
 *
 *  Function:   Compares two strings and returns TRUE if identical.
 *
 *  Notes:      Allows the use of character (?) and string (~) wildcards in
 *              the specification of the expected string.
 *
 *              THE ORDER OF EXPECTED AND ACTUAL POINTERS IS IMPORTANT
 *              WHEN THE WILDCARDS ARE USED.
 *
 *              THE EXPECTED STRING MUST BE IN CODE MEMORY AND THE
 *              ACTUAL STRING MUST BE IN XDATA.
 *
 *****************************************************************************/

bit user_strcmp(unsigned char code *er, unsigned char xdata *ar) large
{                                                   // ar = actual_string
                                                    // er = expected_string
    bit    match = TRUE;                            //
                                                    //
    do                                              // String compare loop
    {                                               //
        if( *er == '?' )                            // If a character wildcard is
        {                                           // in the expected string:
            er++;                                   // don't test this actual char
        }                                           //
        else if( *er == '~' )                       // If a string wildcard:
        {                                           //
            er++;                                   // Start the inner loop
                                                    // looking for the next
                                                    // char after the ~.
            while( (*ar != *er ) && ( *ar != '\0')) // Inner loop searches
            {                                       // through the actual string
                                                    // until either a match with
                                                    // the char after the expected
                ar++;                               // or the end of the actual
            }                                       // string.
                                                    //
                                                    // If the loop terminated due
                                                    // to the actual \0 char
            if( *er != *ar )                        // but we were expecting
            {                                       // something else
                match = FALSE;                      // we need to test again to
            }                                       // catch this condition.
            if( *er != '\0' )                       //
            {                                       //
                er++;                               //
            }                                       //
        }                                           //
        else                                        // Normal test (No wildcard)
        {                                           //
            if( *er != *ar )                        //
            {                                       //
                match = FALSE;                      //
            }                                       //
            if( *er != '\0' )                       //
            {                                       //
                er++;                               //
            }                                       //
        }                                           //
    }                                               //
    while( ( *ar++ != '\0') && (match) );           //
                                                    //
    if( *er != '\0' )                               //
    {                                               //
        match = FALSE;                              //
    }                                               //
                                                    //
    return( match );                                //
}                                                   //

"You may find the code below useful ...

Input:      Pointers to the 'expected' and 'search' strings."