C for each pulling from vector elements

Question

I am trying to do a foreach on a vector of attacks  each attack has a unique ID say  1-3   The class method takes the keyboard input of 1-3   I am trying to use a foreach to run through my elements in m attack to see if the number matches  if it does    do something   The problem I m seeing is this    a for each  statement cannot operate on an expression of type  std  vector lt Attack   Am I going about this totally wrong  I have C  experience and is kind of what I m basing this on  any help would be appreciated    My code is as follows    In header  vector lt Attack gt  m attack    In class  int Player  useAttack  int input         for each  Attack  attack in m attack     Problem part                   Psuedo for following action         if  attack- gt m num    input                          For the found attack  do it s damage             attack- gt makeDamage

User · Accepted Answer

For next examples assumed that you use C++11. Example with ranged-based for loops:

for (auto &attack : m_attack) // access by reference to avoid copying
{  
    if (attack->m_num == input)
    {
        attack->makeDamage();
    }
}

You should use const auto &attack depending on the behavior of makeDamage().

You can use std::for_each from standard library + lambdas:

std::for_each(m_attack.begin(), m_attack.end(),
        [](Attack * attack)
        {
            if (attack->m_num == input)
            {
                attack->makeDamage();
            }
        }
);

If you are uncomfortable using std::for_each, you can loop over m_attack using iterators:

for (auto attack = m_attack.begin(); attack != m_attack.end(); ++attack)
{  
    if (attack->m_num == input)
    {
        attack->makeDamage();
    }
}

Use m_attack.cbegin() and m_attack.cend() to get const iterators.

User · Answer

The for each syntax is supported as an extension to native c   in Visual Studio    The example provided in msdn   include  lt vector gt   include  lt iostream gt   using namespace std   int main        int total   0     vector lt int gt  v 6     v 0    10  v 1    20  v 2    30    v 3    40  v 4    50  v 5    60     for each int i in v        total    i         cout  lt  lt  total  lt  lt  endl       works in VS2013  is not portable cross platform but gives you an idea of how to use for each    The standard alternatives  provided in the rest of the answers  apply everywhere  And it would be best to use those

User · Answer

C   does not have the for each loop feature in its syntax  You have to use c  11 or use the template function std  for each   struct Function       int input      Function int input   input input         void operator   Attack amp  attack            if attack- gt m num    input  attack- gt makeDamage             Function f input   std  for each m attack begin    m attack end    f

User · Answer

This is how it would be done in a loop in C   11       for  const auto amp  attack   m attack                  if  attack- gt m num    input                        attack- gt makeDamage                      There is no for each in C    Another option is to use std  for each with a suitable functor  this could be anything that can be called with an Attack  as argument

[c++] C++ for each, pulling from vector elements

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