string in c18 compiler

[td micro]

hi...
in my project, i have to read string from pc to USART in PIC 18F. we are using C18 compiler. and then we have to compare it with one predefined string.
i saw
getsUSART(a,7); but in this, we have to add exact 7 characters.but the length of the string is unknown..so how can we read one string with unknown length?
and how to compare it with predefined string? plz help me.....
thank you

 

[ponnus]

Hai,
If the length of the string is unknown, you can use getcUSART() to read a single byte.
You can either write an ISR for reading bytes from UART or use the function in a loop (it should contiuously read whenever the data is ready).
The byte received should be stored to a buffer and increment the index of the buffer to store the next byte.
Data transfer can be paused, either when the buffer is full or after a timeout period.

You can compare the strings using strcmp() function,which is in string.h file

 

[td micro]

hi,
thanks for reply

You can compare the strings using strcmp() function,which is in string.h file

i think, we cant compare like this
strcmp(buffer[], "hallooo");
by using strcmp, we cant compare with one predefined string.so can you please help me to compare whether the input string is "hallooo"

 

[ponnus]

Hai,
Did you tried type casting the parameters of strcmp() as const char* or rom unsigned char*.

Otherwise you can write a function like this pseudo code:

int fn(char* b1,char* b2)
{
    while((*b1 != '\0') && (*b2 != '\0))
   {
     if(*b1 != *b2)
       return false;
    b1++;
    b2++;
   }
  return true;
}