These are the one-line ways:
1 \Hello World && uses set textmerge on, not the same as text..endtext ;-)
2 ? "Hello world"
3 Error "Hello World!"
4 [at] x, y SAY "Hello world"
5 input "Hello World" to x -- wgcs
6 Wait Window "Hello World"
7 MessageBox ("Hello World")
8 SET MESSAGE TO "Hello world"
9 _screen.Print("Hello World")
10 ACCEPT "Hello World" TO lcVar && -- Andy Kramek
11 _screen.Caption="Hello world"
12 _vfp.StatusBar = "Hello World"
13 InputBox("?","Hello World","") && -- Andy Kramek
14 KEYBOARD "{Ctrl+F2}Hello world!"
15 Assert .F. Message "Hello World" && Debugging, not allowed in interactive mode
16 DEFINE PAD HelloWorld OF _MSYSMENU PROMPT "Hello World"
17 MODIFY FILE "Hello World." && -- Geoff Franklin - wishing he hadn't started this.
18 WAIT "Hello World" TO lcVar && -- And before you ask: No, it's not the same as WAIT WINDOW 19 19 [at] x, y GET HelloWorld DEFAULT "Hello World"
20 ? CHRTRAN(CHRTRAN('67882 3258D', '6789', 'HELP()'), '12345','POWER()')
21 select '' as Helloworld from (_foxcode) where .f. && -- Phil Spencer
22 oResponse.Write([Hello World]) && (to web browser from VFP/IIS) -- Claude Fox
23 SELECT "HelloWord" AS HelloWorld FROM (SYS(2005)) WHERE RECNO() = 1 && -- Luis Maria Guayan