从向量中擦除元素，然后向量中填充struct

Question

something like this:

struct mystruct 
{
  char straddr[size];
  int port;
  int id;
  .......
};

mystruct s1={......};
mystruct s2={......};
mystruct s3={......};

vector test;
test.emplace_back(s1);
test.emplace_back(s2);
test.emplace_back(s3);

now i want to erase the element with straddr="abc" and port = 1001. what should i do? And i don't want to do it like this.

    for(auto it = test.begin();it != test.end();)
   {
      if(it->port == port && 0 == strcmp(it->straddr,straddr))
         it = test.erase(it);
     else
        it++;
   }

Answer 1

First of all, use std::string instead of char [size] so that you can use == instead of strcmp and other such c-string functions.

Then use std::remove_if() along with erase() as:

test.erase (
    std::remove_if(
        test.begin(), 
        test.end(), 
        [](mystruct const & s) { 
            return s.port == 1001 && s.straddr == "abc"; 
        }
    ), 
    test.end()
);

It is idiomatic solution to your problem and you can read more about it here:

• C++ Idioms/Erase-Remove

Note that this solution will remove all elements from the container for which the predicated returns true . However, if it is known in advance that there will be at most one item matching the predicate, then std::find_if accompanied with erase() would be faster:

auto it = std::find_if(
             test.begin(), 
             test.end(), 
             [](mystruct const & s) { 
               return s.port == 1001 && s.straddr == "abc"; 
             }
          );
if(it != test.end())//make sure you dont pass end() iterator.
    test.erase(it); 

Hope that helps.