Call a function: Difference between revisions
Z comes after P
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Note this task is about methods of calling functions, not methods of [[Function definition|defining functions]], which is a separate topic.
=={{header|ZX Spectrum Basic}}==▼
On the ZX Spectrum, functions and subroutines are separate entities. A function is limited to generating a return value. A subroutine can perform input and output.▼
<lang zxbasic>▼
10 REM functions cannot be called in statement context▼
20 PRINT FN a(5): REM The function is used in first class context▼
30 PRINT FN b(): REM Here we call a function that has no arguments▼
40 REM parameters cannot be passed parameters, however variables are global▼
50 LET n=1: REM This variable will be visible to the called subroutine▼
60 GOSUB 1000: REM subroutines are called by line number and do not have names▼
70 REM subroutines do not return a value, but we can see any variables it defined▼
80 REM subroutines cannot be used in first class context▼
90 REM builtin functions are used in first class context, and do not need the FN keyword prefix▼
100 PRINT SIN(50): REM here we pass a parameter to a builtin function▼
110 PRINT RND(): REM here we use a builtin function without parameters▼
</lang>▼
=={{header|Perl 6}}==
Fundamentally, nearly everything you do in Perl 6 is a function call if you look hard enough.
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There is no difference between calling subroutines and functions in Perl 6, other than that
calling a function in void context that has no side effects is likely to get you a "Useless use of..." warning.
▲=={{header|ZX Spectrum Basic}}==
▲On the ZX Spectrum, functions and subroutines are separate entities. A function is limited to generating a return value. A subroutine can perform input and output.
▲<lang zxbasic>
▲10 REM functions cannot be called in statement context
▲20 PRINT FN a(5): REM The function is used in first class context
▲30 PRINT FN b(): REM Here we call a function that has no arguments
▲40 REM parameters cannot be passed parameters, however variables are global
▲50 LET n=1: REM This variable will be visible to the called subroutine
▲60 GOSUB 1000: REM subroutines are called by line number and do not have names
▲70 REM subroutines do not return a value, but we can see any variables it defined
▲80 REM subroutines cannot be used in first class context
▲90 REM builtin functions are used in first class context, and do not need the FN keyword prefix
▲100 PRINT SIN(50): REM here we pass a parameter to a builtin function
▲110 PRINT RND(): REM here we use a builtin function without parameters
▲</lang>
[[Category:Functions and subroutines]]
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