Call a function: Difference between revisions
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→{{header|Fortran}}
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Within a function there are some delicacies. The usual form is to assign the desired result to the name of the variable as in <code>H = A + B</code> where <code>H</code> is the name of the function. However, during evaluation the desired result might be developed over many stages and with reference to prior values. Suppose function H is to combine results from separate statements and it is not convenient to achieve this via one lengthy expression, perhaps because of conditional tests. Something like <lang Fortran> H = A + B
IF (blah) H = 3*H - 7</lang>
As written, the appearance of <code>H</code> on the right-hand side of an expression does ''not'' constitute an invocation of function <code>H</code> at all. Some compilers fail to deal with this as hoped, and so one must use a scratch variable such as <
With the belated recognition of recursive possibilities (introduced by Algol in the 1960s) comes the possibility of a function invoking itself. In the above example, <code>H(3.7,5.5,6.6)</code> would clearly be a function invocation (because of the parentheses) whereas <code>H</code> would not be. Actually, Fortran routines have always been able to engage in recursion, it is just the returns that will fail - except on a stack-based system such as the Burroughs 6700 in the 1970s.
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END TYPE MIXED
TYPE(MIXED) LOTS(12000)</lang>
One might hope to try <code>IT = BCHOP(LOTS.NAME,"Fred")</code> where BCHOP is a well-tested function for performing a binary search that should run swiftly. Alas, no. The successive values of NAME are not contiguous while BCHOP expects to receive an array of values that are contiguous. So, the compiler inserts code to copy all the LOTS.NAME elements into such a work area and passes the location of that to BCHOP (which searches it swiftly), then on return, the work area is copied back to LOTS.NAME just in case. This latter can be avoided if within BCHOP its array is given the attribute INTENT(IN) for read-only but the incoming copy still means an effort of order N, while for the search
=={{header|Go}}==
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