Nasal Hello World: Difference between revisions
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== Hello world == | == Hello world == | ||
A simple hello world example in Nasal would be (to be saved in $FG_ROOT/Nasal): | A simple hello world example in Nasal would be (to be saved in [[$FG_ROOT]]/Nasal): | ||
<syntaxhighlight lang="php"> | <syntaxhighlight lang="php"> | ||
# $FG_ROOT/Nasal/hello.nas | # [[$FG_ROOT]]/Nasal/hello.nas | ||
print('Hello World!'); | print('Hello World!'); | ||
</syntaxhighlight> | </syntaxhighlight> |
Revision as of 10:28, 21 March 2013
The FlightGear forum has a subforum related to: Nasal Scripting |
Nasal scripting |
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Nasal internals |
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Memory Management (GC) |
Hello world
A simple hello world example in Nasal would be (to be saved in $FG_ROOT/Nasal):
# [[$FG_ROOT]]/Nasal/hello.nas
print('Hello World!');
This will show the "Hello World" string during startup in the console window. The hash sign (#) just introduces comments (i.e. will be ignored by the interpreter).
Note: Script-specific symbols such as global variables (or functions) will be put into a scope (namespace) based on the script's name, scripts embedded via aircraft-set.xml files can separately specify a corresponding module name (see Howto: Make an aircraft for details).
Strings in Nasal can also use double quotes which support escaping:
# hello.nas
print("Hello\nWorld!");
Double quotes support typical escape sequences:
- \n Newline
- \t Horizontal Tab
- \v Vertical Tab
- \b Backspace
- \r Carriage Return
- \f Form feed
- \a Audible Alert (bell)
- \\ Backslash
- \? Question mark
- \' Single quote
- \" Double quote
For example, to print a new line, use:
print ("\n");
To print a quoted string, use:
print ("\"quoted string\"");
and so on.
Single quotes treat everything as literal except for embedded single quotes (including embedded whitespace like newlines).
Nasal strings are always arrays of bytes (never characters: see the utf8 library if you want character-based equivalents of substr() et. al.). They can be indexed just like in C (although note that there is no nul termination -- get the length with size()):