*Stata programming by Example
*Tutorial 2



**Example 1, macro
* 2 ways of assigning something to a macro

*--------------Start Example  1 ----------------*

local a="this is a"       //with the = is limits to 244 characters
display "`a'"

local b "this is b"       //limited to lots of characters see "help limits" for the limit for your flavour of Stata, copies the definition
display "`b'"


*--------------End Example----------------------*



*using "=" limits the length of the macro to 244 characters. Example 2 illustrates this.
*--------------Start Example  2 ----------------*

local a= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local a1= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local a2= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local a3= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local a4= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local b5= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"

local aa="`a'"+"`a1'"+"`a2'"+"`a3'"+"`a4'" +"`a5'"

di "`aa'"    //with the = the length of the macro is limits to 244 characters


local b  "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local b1= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local b2= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local b3= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local b4= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
local b5= "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"

local bb "`b'"  "`b1'"  "`b2'"  "`b3'"  "`b4'"  "`b5'" 

di "`bb'"    //withOUT the = the length of the macro is limits to: see help limits

*--------------End Example----------------------*
help limits




**Example 3, using a macro

*--------------Start Example  3 ----------------*

sysuse auto, clear

local a mpg weight price turn

regress mpg `a'      
summarize `a'
describe `a'

*--------------End Example----------------------*



**Example 4, using a macro
*--------------Start Example  4 ----------------*

sysuse auto, clear

local a mpg weight price turn

regress mpg `a'      

local a=_b[weight]
display "`a'"

*--------------End Example----------------------*



*--------------Start Example  5 ----------------*

local a 1
local b 2
local c 3
local abc= `a'+`b'+`c'
display  "`abc'"
display "a+b+c= " "`abc'"

*--------------End Example----------------------*




*--------------Start Example  6 ----------------*

local a a
local b b
local c c
local abc "`a'`b'`c'"
display "`abc'"

*--------------End Example----------------------*



*global macro
*--------------Start Example  7 ----------------*

global a="this is a"       
display "$a"

*--------------End Example----------------------*
*Warning: only use global macro if local macro do not do the job




*listing macro
*--------------Start Example  8 ----------------*

local a=1
macro list

*--------------End Example----------------------*




*End tutorial 2 - programming Stata