Common STL skills

1. delete an element.

For example, if m IDs are saved in vector vecID, the nth IDs must be deleted.

Traversal is a method, that is, vector: itertor it = vecID. begin (); then ++ it n times.

A better method is: vector: itertor it = vecID. begin () + n; the vector iterator directly supports this offset.

Then, use vecID. erase (it) to delete the element.

 

2. Remove all objects with specific values in a container

1) if the container is a vector, string, or deque, use erase-remove. For example:

C. erase (remove (c. begin (), c. end (), 1963), c. end ());

 

2) If the container is list, use list. remove

// When c is a list, the remove member function is the best method to remove elements with specific values.

C. remove (1963 );

 

3) if the container is a standard associated container, use its erase member function, for example:

// When c is a standard associated container, the erase member function is the best method to remove elements with specific values.

C. erase (1963 );

 

3. Remove all objects in a container that meet a specific criterion

Bool badValue (int x); // Function Definition: returns whether x is "bad"

O if the container is a vector, string, or deque, use the erase-remove_if usage:

// When c is a vector, string, or deque, this is the best way to remove badValue and return a real object.

C. erase (remove_if (c. begin (), c. end (), badValue), c. end ());

O if the container is list, use list. remove_if:

// When c is list, this is the best way to remove badValue and return the real object.

C. remove_if (badValue );

O if the container is a standard associated container, use remove_copy_if and swap.

O if you need to write a circular traversal container element erase, pay attention to the incremental logic of iterator

// Error code: When an element of the container is deleted, all iterators pointing to that element become invalid.

AssocContainer <int> c;

// Do not do this!

For (AssocContainer <int>: iterator I = c. begin (); I! = C. end (); ++ I)

{

If (badValue (* I ))

{

C. erase (I );

}

}

 

// Correct code:

AssocContainer <int> c;

// The third part of the for Loop is empty, and I is auto-incrementing later.

For (AssocContainer <int>: iterator I = c. begin (); I! = C. end ();)

{

If (badValue (* I ))

{

I = c. erase (I); // only applicable to sequential containers. c. erase (I ++) is used for associated containers. void is returned for the associated container erase,

}

Else

{

++ I;

}

} (# Add wonderful)