Posts tagged c++

Its been quite some time (16+ months) I’ve been out of college and started using STL. Trust me, I didn’t know much about STL in college, though I used std::string & std::vector everywhere I could. Now, it seems like I couldn’t (wouldn’t ? ) write a program without using STL at all. A few snippets that I really found useful (and simple) and I regularly use where ever possible.

To output the elements (all / subset) in a container (lets say vector), separated by a delimiter, say new line:

#include <algorithm>

std::copy(v.begin(), v.end(), std::ostream_iterator(std::cout, "\n"));

Want to sort an array? No problem …

#include <algorithm>

std::sort(array, array + lengthOfArray);

Read from the standard input into a vector until the end-of-stream?

#include <algorithm>
#include <iterator>
#include <vector>

typedef std::istream_iterator<int> istream_iterator_int;
std::vector<int> v;
istream_iterator_int start (std::cin);
istream_iterator_int end;
std::back_insert_iterator<vector<int> > dest (v);
std::copy (start, end, dest);

Count the no. of instances an object is found?

#include <algorithm>

size_t count = std::count(v.begin(), v.end(), 42); // Returns no. of elements in v with value 42.

And let me inform you… This is just a grain of what STL can do….

References:

http://www.cs.brown.edu/~jak/proglang/cpp/stltut/tut.html

http://www.cplusplus.com/reference/algorithm/