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docs: some additions to the programming manual

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slederer 2024-10-29 00:08:20 +01:00
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doc/pascalprogramming.md
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@ -39,6 +39,16 @@ The _in_ operator also works for linear arrays, so the _if_ statement will have
Note that the array _in_ operator will be more inefficient for larger ranges (i.e. `'A'..'z'`), but more efficient for sparse sets (i.e. `'A','z'`).
## Break and Continue Statements
Wirth Pascal has no statement to exit a loop. Other Pascal dialects have the _break_ and _continue_ statements to exit the loop or skip to the next iteration.
Tridora-Pascal only supports the _break_ statement at the moment.
## Exit Statement
The _exit_ statement can be used to exit the current procedure or function. If it is a function, the return value of the function is undefined if _exit_ is
used before a return value is assigned.
## I/O
I/O handling in Tridora Pascal is mostly compatible with other Pascal dialects when reading/writing simple variables from/to the console. There are big differences when opening/reading/writing files explicitly.
@ -113,6 +123,22 @@ begin
end;
```
Possible error codes from _IOResult_ are:
|Value|Constant Identifier| Description| Notes |
|---|-------------------|------------|-------|
| 0 | IONoError | no error | |
| 1 | IOFileNotFound | file not found | |
| 2 | IOVolNotFound | volume not found | |
| 3 | IOPathInvalid | path invalid | |
| 4 | IOFileExists | file already exists | |
| 5 | IOFileClosed | file closed | |
| 6 | IOSeekInvalid | seek invalid | |
| 7 | IONoSpace | no space | |
| 8 | IOReadOnly | file is readonly | |
| 9 | IOInvalidOp | invalid operation | |
| 10 | IOInvalidFormat | invalid format | when parsing numbers with _read_ |
| 11 | IOUserIntr | interrupted by user | program terminated by ^C, not visible from _IOResult_ |
### Read, Readln and Line Input
In Turbo Pascal, using _read_ (and _readln_) from the console always waits until a complete line has been entered.
Tridora-Pascal handles this like UCSD-Pascal, that is, it immediately
@ -136,6 +162,12 @@ var c:char;
```
## Labels
In Wirth Pascal, labels must be numbers. Other Pascal dialects also allow normal identifiers (i.e. start with letters then letters and digits).
Tridora-Pascal only allows identifiers as labels.
## Compiler Directives
Tridora-Pascal understands a small number of compiler directives which are introduced as usual with a comment and a dollar-sign. Both comment styles can be used.