C++ - Loop for ranged-based

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C++ - Loop for ranged-based

The for ranged-based loop was introduced from C++11 and has a slightly better performance. It is not always a case to be used, but whenever you can use it! For programmers of other languages loop for ranged-based can be compared to foreach.

In today’s cpp::daily we will show you 5 examples that will facilitate your understanding so you can use them whenever necessary!

01. Foreach style

for( int i : { 11, 2, 9, 17, 89, 12, 13, 52, 8, 4 } ){
  std::cout << i << '\n';
}

02. With vectors and automatic types

std::vector<int> vec = { 11, 2, 9, 17, 89, 12, 13, 52, 8, 4 };
for( auto &elem : vec ){
  std::cout << elem << '\n';
}


03. When switched to function templates

#include <iostream>
#include <vector>

template <typename T>
void print( const T& coll ){
  for( auto &elem : coll ){
    std::cout << elem << ' ';
  }
  std::cout << '\n';
}

int main(){
  std::vector<int> vec = { 11, 2, 9, 17, 89, 12, 13, 52, 8, 4 };
  print( vec );
  return 0;
}

04. Range based on vector declarations

std::vector<int> vec = { 11, 2, 9, 17, 89, 12, 13, 52, 8, 4 };
for ( auto pos = vec.begin(); pos != vec.end(); ++pos) {
 std::cout << *pos << '\n'; 
}

05. Adding elements in foreach style

int array[] = { 1, 2, 3 };
long sum = 0;
for ( int x : array ) {
 sum += x;
}

for ( auto elem : { sum, sum * 2, sum * 4 } ) {
  std::cout << elem << '\n';
}

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