Nasal 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 some of the typical escape sequences:

• \n Newline
• \t Horizontal Tab
• \r Carriage Return
• \\ Backslash
• \" Double quote
• \xyy Hexadecimal-specified character (yy stands for two hexadecimal digits; \x is literal)

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()):