| ??? 08/24/06 22:03 Read: times |
#122973 - OK Responding to: ???'s previous message |
Andy Neil said:
Jon Ledbetter said:
So if I do:#define SW1 P_4;Then later in a proceedure or function I can do:Sw1 = 1; // turn on port
delay(20); // delay SW1 = 0; // turn off portBut this doesn't work. It doesn't work because it is not correct! For a start, 'C' is case-sensitive - so SW1 and Sw1 are not equivalent! When you use a #define, it works like this:#define Then, wherever the preprocessor sees , it simply replaces it with In your code above, is SW1 is P_4; - including the semicolon! Thus, after preprocessing, your code becomes (assuming that you intended SW1 in both cases):P_4; = 1; // turn on port delay(20); // delay P_4; = 0; // turn off portand the error is immediately obvious! See: http://www.8052.com/forum/read.phtml?id=29152 I have several references for C, but most use Keil code. This is basic, plain vanilla, bog-standard 'C' - nothing to do with Keil, SDCC, or any other specific implementation! As has already been mentioned, you need to learn the basic 'C' language first, before worrying about the extensions offered by Keil, SDCC, etc... Ok first of all the Sw1 was a typo it should have been SW1. Second, the reference to Keil code was the usage of Px^x vs Px_x Third, the extensions is what makes it useful for a uC, right? That's why I'm giving a try, I don't want to program a PC. I understand I need to learn the basics first. It was just natural to put a ; at the end of the line. Jon |
| Topic | Author | Date |
| SDCC Nooby Question | 01/01/70 00:00 | |
| Ok got it | 01/01/70 00:00 | |
| it\'s ok in Keil | 01/01/70 00:00 | |
| Yes... | 01/01/70 00:00 | |
| The reason is... | 01/01/70 00:00 | |
| C first | 01/01/70 00:00 | |
| Learning C | 01/01/70 00:00 | |
| if this is cut and paste then | 01/01/70 00:00 | |
| Semi-colon was it | 01/01/70 00:00 | |
| C is fidgety about error declaration | 01/01/70 00:00 | |
| Syntax error | 01/01/70 00:00 | |
| Going back and looking... | 01/01/70 00:00 | |
| It means | 01/01/70 00:00 | |
| Preprocessor output | 01/01/70 00:00 | |
| explanation | 01/01/70 00:00 | |
| Semicolon | 01/01/70 00:00 | |
| yes, Andy you are absolutely correct | 01/01/70 00:00 | |
| Semicolon - example | 01/01/70 00:00 | |
| backwards | 01/01/70 00:00 | |
| HUH? | 01/01/70 00:00 | |
| try this | 01/01/70 00:00 | |
| Dallas app notes | 01/01/70 00:00 | |
| False economy | 01/01/70 00:00 | |
| OK | 01/01/70 00:00 | |
| Learning from the tools | 01/01/70 00:00 | |
| #define and the preprocessor | 01/01/70 00:00 | |
| are you sure? | 01/01/70 00:00 | |
Yes! | 01/01/70 00:00 | |
| Hmmm... | 01/01/70 00:00 | |
| SDCC Manual | 01/01/70 00:00 | |
| Err... ya think? | 01/01/70 00:00 | |
| Looks clear enough to me | 01/01/70 00:00 |