logical_not

Library:  General utilities

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A unary function object that returns true if its argument is false

#include <functional>

namespace std {
  template <class T>
  struct logical_not;
}

logical_not is a unary function object. Its operator() returns true if its argument is false. You can pass a logical_not object to any algorithm that requires a unary function. For example, the replace_if() algorithm replaces an element with another value if the result of a unary operation is true. logical_not is used in that algorithm in the following manner:

vector<int> vec1;
.
.
.
void replace_if(vec1.begin(), vec1.end(),
                logical_not<int>(),1);

This call to replace_if() replaces all zeros in the vec1 with 1.

namespace std {

  template <class T>
  struct logical_not : unary_function<T, bool> {
    bool operator() (const T&) const;
  };
}

Function Objects, unary_function

ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 20.3.4