C++ copy specified vector content to another vector

Question

I created a vector:

std::vector<std::string> mero; // earlier it filled with more than 500 data

After that I would like to create another vector which only takes a portion of the mero vector. (example: from 100th to 250th)

score 12 · Accepted Answer · answered Mar 18 '13 at 13:34

12

There's a constructor for std::vector (number 4 in this link) that takes two iterators. It constructs a new vector including all elements from the first iterator (inclusive) to the second iterator (exclusive).

std::vector<std::string> partOfMero(mero.begin() + 100, mero.begin() + 250);

This will include mero[100] through mero[249] in the newly-constructed vector.

answered Mar 18 '13 at 13:34

David Schwartz

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Thanks that works fine! :-) – szuniverse Mar 18 '13 at 13:36
Its confusing it doesnt include 250. The name in the definition says `[first, last]` is confusing – JamesWebbTelescopeAlien Jan 28 '18 at 18:52

score 6 · Answer 2 · answered Mar 18 '13 at 13:37

6

You can get the first iterator using begin, and advance it by whatever amount you need:

vector<int> sub(advance(begin(miro), 100),
                advance(begin(miro), 250));

answered Mar 18 '13 at 13:37

Peter Wood

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+1 for using `begin`/`advance` instead of old `vector::begin`/`vector::operator+`. – Max Truxa Jan 24 '14 at 09:04

juanchopanza · Answer 3 · 2013-03-18T13:40:07.920

std::vector has a constructor that takes two iterators, so you can specify a range to copy:

std::vector<std::string> v1;
std::vector<std::string>::const_iterator first = v1.begin() + 100;
std::vector<std::string>::const_iterator last = v1.begin() + 250;
std::vector<std::string> v2(first, last)

This will construct v2 such that it contains copies of all the elements from v1.begin()+100 to one before v1.begin()+250.

C++ copy specified vector content to another vector

3 Answers3