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c++classstructurepredicate

What is predicate in C++?

Can you give some example or a link to a topic.

Solution

  • A predicate is a C++ function returning a boolean or an object having a bool operator() member. A unary predicate takes one argument, a binary takes two, and so on. Examples of questions predicates can answer for a particular algorithm are:

    • Is this element what we are looking for?
    • Is the first of two arguments ordered first in our order?
    • Are the two arguments equal?

    Almost all STL algorithms take a predicate as last argument.

    You can construct new predicates using standard, self-defined, and/or predicate-making classes (here is a good reference).