Nested function: Difference between revisions
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Console.WriteLine(MakeList(". "));</lang>
=={{header|Fortran}}==
Fortran allows the user to define functions (and subroutines also) but from the start these are compiled as separate items and cannot themselves contain the definition of another function (or subroutine) - except for the special form allowing the definition of what is called an arithmetic statement function, such as follows:<lang Fortran> FUNCTION F(X)
REAL X
DIST(U,V,W) = X*SQRT(U**2 + V**2 + W**2) !The contained function.
T = EXP(X)
F = T + DIST(T,SIN(X),ATAN(X) + 7) !Invoked...
END</lang>
This (deranged) function contains within it the definition of function DIST (which must be achieved in a single arithmetic statement), and which has access to all the variables of its containing function as well as its own parameters. Such functions are defined following any declarations of variables, and precede the executable statements.
With the advent of F90 comes the CONTAINS statement, whereby within a function (or subroutine) but oddly, at its ''end'' (but before its END) appears the key word CONTAINS, after which further functions (and subroutines) may be defined in the established manner. These have access to all the variables defined in the containing routine, though if the contained routine declares a name of the containing routine then that outside name becomes inaccessible.
Such contained routines are not themselves allowed to contain routines, so that the nesting is limited to two levels - except that arithmetic statement functions are available, so that three levels could be employed. Languages such as Algol, pl/i, Pascal, etc. impose no such constraint.
=={{header|Go}}==
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