In this task, the goal is to take a combined set of elements and apply a function to each element.
C-style Array:
#include <iostream> //cout for printing #include <algorithm> //for_each defined here //create the function (print the square) void print_square(int i) { std::cout << i*i << " "; } int main() { //create the array int ary[]={1,2,3,4,5}; //stl for_each std::for_each(ary,ary+5,print_square); return 0; } //prints 1 4 9 16 25
std::vector
#include <iostream> // cout for printing #include <algorithm> // for_each defined here #include <vector> // stl vector class // create the function (print the square) void print_square(int i) { std::cout << i*i << " "; } int main() { // create the array std::vector<int> ary; ary.push_back(1); ary.push_back(2); ary.push_back(3); ary.push_back(4); ary.push_back(5); // stl for_each std::for_each(ary.begin(),ary.end(),print_square); return 0; } //prints 1 4 9 16 25
More tricky with binary function
#include <iostream> // cout for printing #include <algorithm> // for_each defined here #include <vector> // stl vector class #include <functional> // bind and ptr_fun // create a binary function (print any two arguments together) template<class type1,class type2> void print_juxtaposed(type1 x, type2 y) { std::cout << x << y; } int main() { // create the array std::vector<int> ary; ary.push_back(1); ary.push_back(2); ary.push_back(3); ary.push_back(4); ary.push_back(5); // stl for_each, using binder and adaptable unary function std::for_each(ary.begin(),ary.end(),std::bind2nd(std::ptr_fun(print_juxtaposed<int,std::string>),"x ")); return 0; } //prints 1x 2x 3x 4x 5x
Boost.Lambda
using namespace std; using namespace boost::lambda; vector<int> ary(10); int i = 0; for_each(ary.begin(), ary.end(), _1 = ++var(i)); // init array transform(ary.begin(), ary.end(), ostream_iterator<int>(cout, " "), _1 * _1); // square and output
C++11
#include <vector> #include <iostream> #include <algorithm> #include <iterator> int main() { std::vector<int> intVec(10); std::iota(std::begin(intVec), std::end(intVec), 1 ); // Fill the vector std::transform(std::begin(intVec) , std::end(intVec), std::begin(intVec), [](int i) { return i * i ; } ); // Transform it with closures std::copy(std::begin(intVec), end(intVec) , std::ostream_iterator<int>(std::cout, " ")); std::cout << std::endl; return 0; }
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