sysutils: what changed
Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.
Title: sysutils
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| 1 | + | The [[Unit|unit]] **`sysUtils`** shipped with the [[FPC|FPC’s]] default [[RTL|run-time library]] provides many system utilities. It attempts to be as compatible to [[Delphi|Delphi’s]] `sysUtils` unit as possible. However, the FPC version is available on [[Platform list|all platforms that the FPC supports]]. It does not contain any Windows-related routines or other highly platform-specific functionality. | |
| 2 | + | ||
| 3 | + | ## Notable functionality | |
| 4 | + | ||
| 5 | + | - [[Format function|format]] | |
| 6 | + | - [[Executing External Programs|executeProcess for executing external programs]] | |
| 7 | + | - several routines ensuring productive use of [[TDateTime|tDateTime]] | |
| 8 | + | - [type helpers for all basic data types](https://www.freepascal.org/docs-html/rtl/sysutils/typehelpers.html) | |
| 9 | + | - [[FreeAndNil|freeAndNil]] | |
| 10 | + | - routines to access [[Command line parameters and environment variables|environment variables]] | |
| 11 | + | ||
| 12 | + | ## Caveats | |
| 13 | + | ||
| 14 | + | [If the `sysUtils` unit is included](https://www.freepascal.org/docs-html/rtl/system/runtimeerrors.html), all [[runtime error|run-time errors]] become [[Exceptions|exceptions]], which virtually forces you to use a [[Compiler Mode|compiler mode]] (or [[modeswitch|mode switch]]) that allows exception treatment. To catch an exception by its name you will need to include `sysUtils`, even though the module itself does not use any of the included system utilities. | |
| 15 | + | ||
| 16 | + | Changing run-time errors to exceptions has a *global* effect. The following program will terminate with an uncaught *exception*, even though it does not list `sysUtils` in its `uses`-clause: The `sysUtils` unit is *implicitly* included via the [`strUtils` unit](https://www.freepascal.org/docs-html/rtl/strutils/index.html): | |
| 17 | + | ||
| 18 | + | ``` pascal | |
| 19 | + | program implicitSysUtilsCaveat(input, output, stdErr); | |
| 20 | + | uses | |
| 21 | + | strUtils; | |
| 22 | + | var | |
| 23 | + | x: file of char; | |
| 24 | + | c: char; | |
| 25 | + | begin | |
| 26 | + | // deliberately cause an error for demonstration purposes | |
| 27 | + | read(x, c); | |
| 28 | + | end. | |
| 29 | + | ``` | |
| 30 | + | ||
| 31 | + | Also, if [[Size Matters|size matters]], using `sysUtils` is by design not the smartest choice. | |
| 32 | + | ||
| 33 | + | ## See also | |
| 34 | + | ||
| 35 | + | - [`sysUtils` reference](https://www.freepascal.org/docs-html/rtl/sysutils/index.html) | |
| 36 | + | - [Delphi’s `sysUtils` unit](http://docwiki.embarcadero.com/Libraries/Sydney/en/System.SysUtils) | |
| 37 | + | - [[libc library]] | |
| 38 | + | - [[System unit|system unit]] | |
| 39 | + | ||
| 40 | + | --- | |
| 41 | + | *From the Free Pascal wiki, page "sysutils", as it stood on 2021-02-06 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |