Hello everyone,

While programming for the internet, I had to do lots of text processing, so I decided to benchmark the various methods of using variables. Thought I'd share my conclusions with you.

Conclusion:
If you are accessing string variables in a loop, avoid arrays and class variables.

1. Class variables are 50 times slower than local vars.
2. Arrays are sometimes 100 times slower than local vars. This was a surprise.
3. The overhead of using a function call with RETURN is minimal.
4. Call by reference (@var) is the slowest. 160 times slower than local vars. Probably best to avoid. This was a B-I-G surprise for me.
5. Global variables are just as fast as local vars.


RESULTS

Test method: Append long string to variable 1000 times.


Example:
timert = seconds()
str = ''
for i = 1 to 1000
str = str + '1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'
endfor
outp('BASELINE=',seconds() - timert)

Results:
Append to local var 1000 times: 0.03 secs
Append to class var 1000 times: 1.35 secs
Append to 6th element of array 1000 times: 3.12 secs
Call a function by reference to append string: 3.20 secs
for i = 1 to MAXNUM
bmCallByRef(@str) && this appends to str by ref
endfor

Call a function that returns a string: 0.13 secs
for i = 1 to MAXNUM
str = str + bmReturn() && returns a string
endfor

Use a global variable in a function: 0.07 secs


================ SOURCE CODE BELOW
* You might have to replace outp with you own messagebox function
* Find out which parameter passing method is fastest
FUNCTION HTMLBenchmark1
local timert,i,str
public gBMStr

*!* BASELINE=0.03
*!* bmClassStr=1.35
*!* bmArray=3.12
*!* BMCALLBYREF=3.20
*!* BMRETURN=0.13
*!* BMGLOBAL=0.07
*!* for 1000 iterations

#define MAXNUM 1000
outp("Starting ",MAXNUM," iterations")

timert = seconds()
str = ''
for i = 1 to MAXNUM
str = str + ;
'1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'
endfor
outp('BASELINE=',seconds() - timert)

o = createobject('wwBM')
timert = seconds()
for i = 1 to MAXNUM
o.mStr = o.mStr + ;
'1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'
endfor
outp('bmClassStr=',seconds() - timert)

timert = seconds()
local arr[2,4]
arr[2,3] = ''
for i = 1 to MAXNUM
arr[2,3] = arr[2,3] + ;
'1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'
endfor
outp('bmArray=',seconds() - timert)

timert = seconds()
str = ''
for i = 1 to MAXNUM
bmCallByRef(@str)
endfor
outp('BMCALLBYREF=',seconds() - timert)

timert = seconds()
str = ''
for i = 1 to MAXNUM
str = str + bmReturn()
endfor
outp('BMRETURN=',seconds() - timert)

timert = seconds()
gBMStr = ''
for i = 1 to MAXNUM
BMGLOBAL()
endfor
outp('BMGLOBAL=',seconds() - timert)

ENDFUNC

DEFINE CLASS wwBM as CUSTOM
mOther = .f.
mFun = .f.
mStr = ''
mHaha = .f.
ENDDEF

FUNCTION BMGLOBAL()
gBMStr = gBMStr + ;
'1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'
FUNCTION bmCallByRef(z)
z = z + ;
'1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'

FUNCTION bmReturn()
local z
z = ;
'1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890'
return z