Книга: Standard Template Library Programmer

project1st

project1st<Arg1, Arg2>

Category: functors

Component type: type

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.

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()));
}

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.

Adaptable Binary Function

None.

binary_function<Arg1, Arg2, Arg1>

All of project1st's members are defined in the Adaptable Binary Function requirements. project1st does not introduce any new members.

Function objects, identity, project2nd, select1st, select2nd

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