std::transform
From Cppreference
| Defined in header
<algorithm> | ||
| template< class InputIterator, class OutputIterator, class UnaryOperation >
OutputIterator transform( InputIterator first1, InputIterator1 last1, | (1) | |
| template< class InputIterator1, class InputIterator2, class OutputIterator, class BinaryOperation >
OutputIterator transform( InputIterator1 first1, InputIterator1 last1, | (2) | |
Applies the given function to a range and stores the result in another range, beginning at d_first. In the first version unary operation unary_op is applied to the range, defined by [first1, last1). In the second version binary operation binary_op is applied to pairs of elements from two ranges: one defined by [first1, last1) and other beginning at first2.
Contents |
Parameters
| first1, last1 | - | the first range of elements to transform | |||||||||
| first2 | - | the beginning of the second range of elements to transform | |||||||||
| d_first | - | the beginning of the destination range | |||||||||
| unary_op | - | unary operation function object that will be applied. The signature of the function should be equivalent to the following:
The signature does not need to have const &. | |||||||||
| binary_op | - | binary operation function object that will be applied. The signature of the function should be equivalent to the following:
The signature does not need to have const &. | |||||||||
Return value
output iterator to the element past the last element transformed.
Equivalent function
| First version: |
|---|
template<class InputIterator, class OutputIterator, class UnaryOperation> OutputIterator copy(InputIterator first1, InputIterator last1, OutputIterator d_first, UnaryOperation unary_op) { while (first1 != last1) { *d_first++ = unary_op(*first1++); } return d_first; } |
| Second version: |
template<class InputIterator1, class InputIterator2, class OutputIterator, class BinaryOperation> OutputIterator copy(InputIterator first1, InputIterator last1, InputIterator first2, OutputIterator d_first, BinaryOperation binary_op) { while (first1 != last1) { *d_first++ = binary_op(*first1++, *first2++); } return d_first; } |
Example
The following code uses transform to convert a string to uppercase using the toupper function:
#include <string> #include <cctype> #include <algorithm> #include <iostream> int main() { std::string s("hello"); std::transform(s.begin(), s.end(), s.begin(), (int (*)(int))std::toupper); std::cout << s; return 0; }
Output:
HELLO
Complexity
1) exactly std::distance(first1, last1) applications of unary_op
2) exactly std::distance(first1, last1) applications of binary_op
See also
| applies a function to a range of elements (function template) | |
