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66 lines
2.6 KiB
Markdown
66 lines
2.6 KiB
Markdown
**RUN** is a control flow statement that clears and restarts the program currently in memory or executes another specified program.
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The multi-modular technique goes back to when QBasic and QuickBASIC had module size constraints. In QB64 it has been implemented so that that older code can still be compiled, though **it is advisable to use single modules for a single project (not counting [$INCLUDE]($INCLUDE) libraries), for ease of sharing and also because the module size constraints no longer exist.**
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## Syntax
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> **RUN** [{*line_number* | *filespec$*}] [*command_parameter(s)*]
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## Parameter(s)
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* *line number* specifies a line number in the main module code.
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* An optional *filespec* specifies a program to load into memory and run.
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* BAS or EXE extensions are assumed to be the same as the calling module's extension, EXE or BAS (QBasic only).
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* *file names specs* with other extensions must use the full filename. No extension requires a dot.
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* In **QB64** *command line parameters* can follow the program file name and be read using the [COMMAND$](COMMAND$) function later.
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## Usage
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* The starting [line number](line-number) MUST be one used in the main module code, even if RUN is called from within a SUB or FUNCTION.
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* If no line number is given the currently loaded program runs from the first executable line.
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* In **QB64** RUN can open any kind of executable program and provide case sensitive program specific parameters.
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* Recommended practice to run external programs is to use [SHELL](SHELL).
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* RUN closes all open files and closes the invoking program module before the called program starts.
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* RUN resets the [RANDOMIZE](RANDOMIZE) sequence to the starting [RND](RND) function value.
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* **Note: Calling RUN repeatedly may cause a stack leak in QB64 if it is called from within a [SUB](SUB) or [FUNCTION](FUNCTION). Avoid when possible.**
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## Example(s)
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Shows how RUN can reference multiple line numbers in the main module code. No line number executes first code line.
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```vb
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PRINT " A", " B", " C", " D"
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10 A = 1
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20 B = 2
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30 C = 3
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40 D = 4
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50 PRINT A, B, C, D
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60 IF A = 0 THEN 70 ELSE RUN 20 'RUN clears all values
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70 IF B = 0 THEN 80 ELSE RUN 30
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80 IF C = 0 THEN 90 ELSE RUN 40
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90 IF D = 0 THEN 100 ELSE RUN 50
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100 PRINT
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INPUT "Do you want to quit?(Y/N)", quit$
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IF UCASE$(quit$) = "Y" THEN END ELSE RUN 'RUN without line number executes at first code line
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```
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```text
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A B C D
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1 2 3 4
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0 2 3 4
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0 0 3 4
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0 0 0 4
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0 0 0 0
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Do you want to quit?(Y/N)_
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```
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## See Also
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* [CHAIN](CHAIN), [SHELL](SHELL)
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* [COMMAND$](COMMAND$)
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