.\" ident @(#)for_each.3
.\" Standard Template Library
.\" $$RW_INSERT_HEADER "slyrs.man"
.TH for_each 3C++ "02 Apr 1998" "Rogue Wave Software" "-"
.ce2
Standard C++ Library   
Copyright 1998, Rogue Wave Software, Inc.   

.SH NAME

\f2for_each\fP

\ - Applies a function to each element in a range.



.SH  SYNOPSIS


.br
#include <algorithm>
.br
template <class InputIterator, class Function>
.br
void for_each(InputIterator first, InputIterator last,
.RE
.RS 14
Function f);



.SH  DESCRIPTION


The for_each algorithm applies function \f2f\fP to all members of the sequence in the range \f2[first, last)\fP, where \f2first\fP and \f2last\fP are iterators that define the sequence. Since this a non-mutating algorithm, the function \f2f\fP cannot make any modifications to the sequence, but it can achieve results through side effects (such as copying or printing). If \f2f\fP returns a result, the result is ignored.



.SH  COMPLEXITY


The function \f2f\fP is applied exactly \f2last - first\fP times.



.SH  EXAMPLE



.RE
.RS 0
//
.br
// for_each.cpp 
.br
//
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#include <vector>
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#include <algorithm>
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#include <functional>
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#include <iostream>
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using namespace std;
.br

.RE
.RS 1
// Function class that outputs its argument times x
.RE
.RS 0
template <class Arg>
.br
class out_times_x :  private unary_function<Arg,void>
.RE
.RS 1
{
.RE
.RS 2
private:
.RE
.RS 5
Arg multiplier;
.RE
.RS 0

.RE
.RS 2
public:
.RE
.RS 5
out_times_x(const Arg& x) : multiplier(x) { }
.br
void operator()(const Arg& x) 
.RE
.RS 9
{ cout << x * multiplier << " " << endl; }
.RE
.RS 1
};
.RE
.RS 0

.br
int main()
.RE
.RS 1
{
.RE
.RS 2
int sequence[5] = {1,2,3,4,5};  
.RE
.RS 0

.br

.RE
.RS 3
// Set up a vector
.RE
.RS 2
vector<int> v(sequence,sequence + 5);
.RE
.RS 0

.RE
.RS 3

.br
// Setup a function object 
.RE
.RS 2
out_times_x<int> f2(2);
.RE
.RS 0

.RE
.RS 3
for_each(v.begin(),v.end(),f2);   // Apply function
.RE
.RS 0

.RE
.RS 2
return 0;
.RE
.RS 1
}

.br
.RE
.RS 0
Program Output



.RE
.RS 0

.br
2 
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4 
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6 
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8 
.br
10



.SH  WARNINGS


If your compiler does not support default template parameters, then you always need to supply the \f2Allocator\fP template argument. For instance, you have to write:

\f2vector<int, allocator<int> >\fP

instead of:

\f2vector<int>\fP

If your compiler does not support namespaces, then you do not need the using declaration for \f2std\fP.



.SH  SEE ALSO


Algorithms, Function_Objects