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Forum Index : Microcontroller and PC projects : Function must be called with 1 argument
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| SteveP Newbie  Joined: 21/03/2013 Location: United StatesPosts: 19 |
It seems a Function must be called with at least one argument. Var1=2 Print MyFcn Function MyFcn(arg1) Print "inside fcn" MyFcn = Var1 * 10 End Function Calling this function as MyFcn does not print the "inside fcn" and the return value is 0 Calling it as MyFcn(1) does print "inside fcn" and returns 20 Declaring MyFcn as Function MyFcn instead of Function MyFcn(arg1) also does not execute and returns 0 Steve |
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Geoffg Guru  Joined: 06/06/2011 Location: AustraliaPosts: 3165 |
When you used Print MyFun the interpreter thought that MyFun was a variable so it created it and returned its initial value (zero). You should use: Print MyFcn() If you want to declare a function with no arguments you should use: Function MyFcn() ... End Function Geoff Geoff Graham - http://geoffg.net |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Functions are not subroutines so you always need the (). It should actually throw an error instead of returning 0. MyFunc is a variable and MyFunc(arg1) a function, both existing at the same time. Very undesireable. Tested like this [code] Var1=2 'Both lines should fail as MyFcn is defined as a function and no more variable with the same name should be possible. MyFcn = 10 'Error: Cannot assign a value to a function Print MyFcn 'Error: Function should be called with () 'The right way to call a function 'with or without arguments is fine' Print MyFcn() Function MyFcn(arg1) Print "inside fcn" MyFcn = Var1 * 10 End Function [/code] It will output: 10 inside fcn 4 Microblocks. Build with logic. |
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| shoebuckle Senior Member  Joined: 21/01/2012 Location: AustraliaPosts: 189 |
The language is so forgiving that even the following use of the word "OUTPUT" is tolerated, not that I am suggesting you write code like this. It is gross but interesting! Output$="output.tst"
data 1,2,3,4,5 Data "one","two","three","four","five" Dim output(5) Dim Output$(5) for I=1 to 5 Read output(i) Next For i=1 to 5 read Output$(i) Next output=1 Open output$ for output as output for i=1 to 5 print #output, Output(i),Output$(i) Next Close output Cheers, Hugh |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
:0 That is some output. 
No need to obfuscate that piece of code. 
Flexibility is good. Forgiving also some times. Difficult to draw a line what should and should not be acceptable. My 'line' is allowing variable names and function names to be the same. And i think BASIC should be stricter then other languages because it is one of the languages people use to learn programming. Errors will then be very helpful. With interpreted languages anything is a 'runtime' error. One of the shortcoming because errors can stay hidden a long time. I think that the OP's case should be handled as an error, not a feature. In the case of MMBasic it is possible to detect variable names and function names because it does a scan for subroutine and function names when you run a program. This scan fills a lookup table to speed up execution. If you have to check every variable name against this list you would be able to detect the variable name/function name but at some execution cost. Microblocks. Build with logic. |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
If I remember correctly, (in languages in general) : if there is no error a function should return a definite value. The datatype of the returned value is usually specified, which allows the returned value to be checked against the datatype for error trapping, important for robust operation. So a declaration of some sort, using the function name, is required to specify the return datatype. So, allowing a function and variable to have the same name invites bugs and gremlins to creep in via the ambiguity. (I just use aerogard to be sure, to be sure  )
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djuqa Guru Joined: 23/11/2011 Location: AustraliaPosts: 447 |
Best programming practice would be to have a convention naming your variables & functions so there can be no confusion. VK4MU MicroController Units |
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