project1st<Arg1, Arg2>
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| Category: functors |
Component type: type |
Description
Project1st is a function object that takes two arguments and
returns its first argument; the second argument is unused.
It is essentially a generalization of
identity to the case of a Binary Function.
Example
int main()
{
vector<int> v1(10, 137);
vector<char*> v2(10, (char*) 0);
vector<int> result(10);
transform(v1.begin(), v1.end(), v2.begin(), result.begin(),
project1st<int, char*>());
assert(equal(v1.begin(), v1.end(), result.begin()));
}
Definition
Defined in the standard header functional, and in the nonstandard
backward-compatibility header function.h.
This function object is an SGI extension; it is not part of the C++
standard.
Template parameters
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Parameter
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Description
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Default
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Arg1
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project1st's first argument type, and its result type.
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Arg2
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project1st's second argument type.
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Model of
Adaptable Binary Function
Type requirements
None.
Public base classes
binary_function<Arg1, Arg2, Arg1>
Members
New members
All of project1st's members are defined in the
Adaptable Binary Function
requirements. project1st does not introduce any new members.
Notes
See also
Function objects, identity, project2nd,
select1st, select2nd
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