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( C++ ) Transform_if

My modification of std::transform to make it work with a predicate.

Prefer algorithms over hand-written loops [0] [1] [2] . View Exercise #9: No for-loops to learn how to remove hand-written loops .

Transform_if function definition

Simplified from the STL that ships with C++ Builder 6.0.

View the Transform_if function definition in plain text.

//From http://www.richelbilderbeek.nl/CppTransform_if.htm

template <

class InputIter,

class OutputIter,

class Predicate,

class UnaryOperation

>

const OutputIter Transform_if(

InputIter first,

const InputIter last,

OutputIter result,

const Predicate pred,

const UnaryOperation opr)

{

for ( ; first != last; ++first, ++result)

*result = pred(*first) ? opr(*first) : *first;

return result;

}

//From http://www.richelbilderbeek.nl/CppTransform_if.htm

template <

class InputIter1,

class InputIter2,

class OutputIter,

class Predicate,

class BinaryOperation>

const OutputIter Transform_if(

InputIter1 first1,

const InputIter1 last1,

InputIter2 first2,

OutputIter result,

const Predicate pred,

const BinaryOperation binary_op)

{

for ( ; first1 != last1; ++first1, ++first2, ++result)

*result = pred(*first1) ? binary_op(*first1, *first2) : *first1;

return result;

}

Example

References

[0]          Bjarne Stroustrup. The C++ Programming Language (3rd edition). ISBN: 0-201-88954-4. Chapter 18.12.1 : 'Prefer algorithms over loops'

[1]          Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Chapter 84: 'Prefer algorithm calls to handwritten loops.'

[2]          Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Chapter 88: 'Prefer function objects over functions as algorithm and comparer arguments.'

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.