Some Useful STL Functions¹

Jeffrey D. Oldham

2000 Feb 12

The Standard Template Library contains many functions working on any container. We highlight a few here.

• find
  • InputIterator find(InputIterator first, InputIterator last, T value)
  • returns the leftmost occurrence of value if present
  • returns last if value not present
  • #include <algorithm>

• copy
  • OutputIterator copy(InputIterator first, InputIterator last, OutputIterator result)
  • copies everything from [first,last) to the container represented by result
  • output container must be large enough already!
  • returns a pointer one past the last changed position
  • #include <algorithm>

• transform
  • OutputIterator tranform(InputIterator first, InputIterator last, OutputIterator result, UnaryFunction op)
  • fills output container with result of op applied to each member of the input container
  • output container must be large enough already!
  • the input and output container can be the same
  • #include <algorithm>

• for_each
  • UnaryFunction for_each(InputIterator first, InputIterator last, UnaryFunction op)
  • applies op to each element in the input container
  • the result of applying op is ignored. That is op should probably be a void function
  • #include <algorithm>

• sort
  • void sort(RandomAccessIterator first, RandomAccessIterator last) or
  • void sort(RandomAccessIterator first, RandomAccessIterator last, ComparatorFunction comp)
  • sorts the specified range
  • uses the specified comparator function comp if present; should be a binary function acting like < for any two container elements
  • uses the container elements' < if comp not specified
  • #include <algorithm>

• accumulate
  • T accumulate(InputIterator first, InputIterator last, T init)
  • T accumulate(InputIterator first, InputIterator last, T init, BinaryFunction op)
  • if op not specified, do + on all the elements starting with an initial value of init, e.g., 0
  • if op specified, do op on all the elements starting with an initial value of init
  • ex: accumulate(v.begin(), v.end(), 0) yields sum of all vector elements
  • ex: accumulate(v.begin(), v.end(), 1, multiplies<int>()) yields product of all vector elements
  • #include <numeric>

• inner_product
  • T inner_product(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, T init)
  • computes the dot product of the two specified containers starting with value init
  • the second container must be at least as large as the first container
  • #include <numeric>

Footnotes

... Functions¹

©2000 Jeffrey D. Oldham . All rights reserved. This document may not be redistributed in any form without the express permission of the author.