.\" ident	@(#)Array_alg:man/generate.3	3.2
.\"
.\" C++ Standard Components, Release 3.0.
.\"
.\" Copyright (c) 1991, 1992 AT&T and UNIX System Laboratories, Inc.
.\" Copyright (c) 1988, 1989, 1990 AT&T.  All Rights Reserved.
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.TH \f3generate\fP \f3Array_alg(3C++)\fP " "
.SH NAME
generate \- apply a given function to every location in an array
.SH SYNOPSIS OF Array_alg.h
.Bf
#include <stddef.h>

    template <class \*(gt>
    void generate(void (*fun)(ptrdiff_t n,\*(gt* p),\*(gt* b,\*(gt* e);

.Be
.SH ASSUMPTIONS
None.
.SH DESCRIPTION
.PP
For each cell in an array
from the leftmost to the rightmost,
\f4generate\f1 
calls function \f4fun\f1 with two arguments: 
(1) the cell index (assuming that the index of the 
first cell is \f20\f1) and 
(2) a pointer to the cell.
.SH COMPLEXITY
.PP
If \f2N\f1 is the size of the array, then
complexity is \f2O(N)\f1.  Exactly \f2N\f1 function 
calls to \f4fun\f1 are made.
.SH EXAMPLE
.PP
In the following example, \f4iota\f1 assigns a 
consecutive integer starting from \f20\f1 to every location 
in the array (similar to the APL function \f4iota\f1):
.Bf

    void zap(ptrdiff_t n, int* address){
	*address = n;
    }
    void iota(int* b, int* e){
	generate(zap, b, e);
    }

.Be
.SH NOTES
Because a Block (see \f3Block(3C++)\f1)
can always be used wherever an array is called for,
Array Algorithms can also be used with Blocks.
In fact, these two components were actually designed 
to be used together.
.SH SEE ALSO
.Bf
\f3intro(.)\f1
\f3fill(.)\f1
\f3for_each(.)\f1
\f3subs(.)\f1
\f3Block(3C++)\f1
.Be