[gromit190]

Hi,


I'm a little bit confused about how a variable is declared and instantiated.

From what I understand, variables can be declared in 3 different ways (example using a StringMap variable):

1. new Float:myFloat
2. decl Float:myFloat
3. Float myFloat

All 3 methods declare a new variable named "myFloat".
Method 1 declares and instantiates myFloat, meaning that there is no previous data in this variable (data is set to 0, for other types everything would be 0, false etc).
Method 2 declares myFloat, but there may be "leftover" data. So depending on what is previously in computer memory, there may be some data in the variable. This can only be done in a local scope (inside a function).
Method 3 ???

The difference between method 1 and 2 are okay I guess, but what's the difference between method 1 and 3?
Is the data set to 0 when using method 3?
If I want a global variable in my plugin, should I use method 1 or 3?

#include <sourcemod>

Float myGlobalVariable;

public void OnPluginStart()
{
    myGlobalVariable = 0.0;
}

[Kailo]

You have to use only one modern way:

PHP Code:

float myFloat; 


All another ways are deprecated syntax.
Before 1.7 was "old syntax" - Pawn syntax.
Since 1.7 SourcePawn have own modern C-like syntax - "Transitional syntax"
Wiki pages:
Introduction to SourcePawn 1.7
SourcePawn Transitional Syntax
Introduction to SourcePawn

[gromit190]

I see, thanks!


I still don't quite see when a variable just reserves some memory, and when it actually clears that memory.


Say I wanted to declare a variable, but I don't want to use any CPU power to wipe pre-existing data. I just want to reserve memory and write to it later.

How is it possible? I guess the "old" way was to use "decl".

[Ilusion9]

Use global variables to keep data and use them later.
Use local variables in functions to work with them only in that function.
Use static variables in functions to work with them only in that function AND keep data for the next call of that function.

PHP Code:


#include <sourcemod>

float myGlobalVariable;

public void OnPluginStart()
{
    myGlobalVariable = 0.0;
} 


this is a global variable, you can use it in every function. the memory will be erased on plugin end

PHP Code:

public void OnPluginStart()
{
    float myGlobalVariable = 0.0;
} 


this is a local variable, you can use it only in that function. the memory its erased.

PHP Code:

public void OnPluginStart()
{
    static float myGlobalVariable = 0.0;
    print myGlobalVariable // after second call this will show 1.0, not 0.0
    myGlobalVariable = 1.0;
} 


this is a static local variable, you can use it only in that function. the memory its still there

[Kailo]

You strongly recommended to not use "decl". "decl" was just experiment for optimization for big size strings and arrays, like char[2048]. Results of experiment: decl not needed.
You have to not think so much about speed or memory then programming with SourcePawn. Just don't think about it. Compiler will make all optimization for you that necessary.
"Zeroing" all memory helps to make language more safety and stable.

[gromit190]

Much appreciated, thank you!