Remote-processing CAMBASIC Manual do Utilizador descarregar pdf (Página 24)

Program ing Tips - 1

How to Maximize Execution Speed

1. Use the pre-compiled variable A% to Z%. In an average program these will run 50% faster. U se as many as

possible, especially in FOR/ NEXT loops and softwar e counters.

For other variables there is a lookup time. To minimize lookup time declare the variables at the beginning of

the progr am to for ce them to be at the beginning of the variable table. Put the var iables which need to

execute fastest at the beginning.

10 A=0:B=0:C=0:A$=""

2. Use constants rather than variables whenever possible in all functions and statements. Except for the pre-

compiled variables above, a “ lookup” time is required.

POKE &9000,4 fastest

POKE A%,B% fast

POKE A,B slowest

3. The speed of execution is independent of the length of the variable name.

4. Place several statements on the same line. This will yield a slight increase in speed at the expense of clarity.

5. Use INC and DEC whenever possible. T hey are much faster than the standard syntax to increment variables.

INC A% fastest

INC A fast

A=A+1 slowest

6. All string operations a re slow. T his is especially true when concatenating strings. When pr inting, avoid

string concatenation.

PRINT A$;B$ fast

PRINT A$+B$ slow

7. Certain mathematical operations have long execution times: multiply, divide, SIN, COS, ATN, SQR, LOG,

EXP and $.

8. Replace a list of conditionals w ith the ON GOT O statem ent:

10 ON X GOTO 200,300,400,500 fast

10 IF X=1 GOTO 200 very slow

20 IF X=2 GOTO 300

30 IF X=3 GOTO 400

40 IF X+4 GOTO 500

9. Even though remarks are not executed, there is a slight amount of overhead to skip over the list number. You

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Remote-processing CAMBASIC Manual do Utilizador Página 24