What is "RetVal=0"?

[gaslouk]

Hi.

What is "RetVal=0"?

RetVal is return Value?

Where i can useit?

Gaslouk.

[Rod]

When you call an API routine it usually returns a value that tells you whether it succeeded or failed. Some API calls do something obvious but even so you still need a way to know it succeeded. Say drawing to a screen, did it succeed or did it fail you cannot see the screen programatically but you can read the return value.

[gaslouk]

Thank you very much Rod but I would like a more specific answer. Let's say "RetVal = FN.somthing()".
Is it a command or something else? What other uses does it have?

Thank you very much for your time.

[Rod]

It is simply a variable named RetVal. Unless you can set its use in better context. Most API calls return a flag saying true or false, programmers store that response in a variety of variable names.

[Walt Decker]

Feb 11, 2023 12:11:58 GMT -5 gaslouk said:

Thank you very much Rod but I would like a more specific answer. Let's say "RetVal = FN.somthing()".
Is it a command or something else? What other uses does it have?

Thank you very much for your time.

In the above "RetVal" is the return from "FUNCTION FN.something()".

For example:

'
GLOBAL SomeNumber
SomeNumber = 36
RetVal = FUNCTION FN.something()

PRINT RetVal
WAIT

'--------------------------------
'--------------------------------

FUNCTION FN.something()

SomeNumber = SomeNumber^1/3
FN.something = SomeNumber
END FUNCTION
'


In other instances it may be the return value from an API or second party DLL call. In these instances "RetVal" may be boolean (zero, not zero); in others "RetVal" may contain 2 numbers since some API functions return a value containing two separate numbers, perhaps coordinates. Some second party DLLs do the same thing. Sometimes the return value is the address or pointer to a block of memory the API or second party DLL created in response to calling the function.

[gaslouk]

Thank you Walt Decker

Feb 11, 2023 16:08:06 GMT -5 Walt Decker said:

Feb 11, 2023 12:11:58 GMT -5 gaslouk said:

Thank you very much Rod but I would like a more specific answer. Let's say "RetVal = FN.somthing()".
Is it a command or something else? What other uses does it have?

Thank you very much for your time.

In the above "RetVal" is the return from "FUNCTION FN.something()".

For example:

'
GLOBAL SomeNumber
SomeNumber = 36
RetVal = FUNCTION FN.something()

PRINT RetVal
WAIT

'--------------------------------
'--------------------------------

FUNCTION FN.something()

SomeNumber = SomeNumber^1/3
FN.something = SomeNumber
END FUNCTION
'


In other instances it may be the return value from an API or second party DLL call. In these instances "RetVal" may be boolean (zero, not zero); in others "RetVal" may contain 2 numbers since some API functions return a value containing two separate numbers, perhaps coordinates. Some second party DLLs do the same thing. Sometimes the return value is the address or pointer to a block of memory the API or second party DLL created in response to calling the function.