how to execute an for loop till the queue is emptyin c++

Question

i need to execute an for loop till the queue is empty my code

queue<string> q;
for(int i=0;i<q.size(),i++)
{
     // some operation goes here
     // some datas are added to queue
}

Solution 1

while (!q.empty())
{
    std::string str = q.front();

    // TODO: do something with str.

    q.pop();
}

Solution 2

It's the same code as the best answer, but using for loop. It looks cleaner for me.

for (; !q.empty(); q.pop())
{
    auto& str = q.front();

    // TODO: do something with str.
}

Comments

[ADreNaLiNe-DJ]

Please add explanations to your answer.

[LemonCool]

for loop doesn't need to instance/initiate a variable, so we just use ';' to tell it do nothing, the condition of the for is until the queue is not empty, at the end of the loop; pop the item from the queue

[yuqli]

Why we need the & here?

[Virus_7]

It's kind of optimisation. std::queue::front() returns a reference to the element that's why there's &. We usually don't need an object copy, we can manipulate the string in-place, as we're popping it out later.