STL Standard Library of C + + learning notes (iii) vector container

The template class vector is a sequential container that encapsulates an array of dynamic sizes, and the sequences it controls are stored in a contiguous array. As with any other type of container, it can hold various types of objects.

Include header file # include <vector> declaration namespace using namespace Std;

Characteristics:

1) Sequential sequence: The elements in the container are sorted in strict linear order. The corresponding element can be accessed by the element's position in the sequence.

2) Dynamic array: Enables quick and direct access to any element in the sequence. Operation to add/remove elements relatively quickly at the end of a sequence.

3) Ability to sense the memory allocator (allocator-aware): The container uses a memory allocator object to dynamically process its storage requirements.

How to use:

1) constructor function

　　Vector (); Create an empty vector such as:vector<int> A;

Vector (int nSize); Create an empty vector with the number of elements nsize such as:vector<int> A (10);

Vector (int nsize,const t& val); Create a vector with a number of elements of nsize and a value of Val such as:vector<string> a (5, "has fun");

Vector (const vector&); Copy (copy) constructor

such as:vector<string> A (5, "has fun");

Vector<string> B (a);

Vector (begin,end); Copy elements from another array [begin,end] range into the vector

such as:intia[6] = { -2, -1, 0, 1, 2, 1024 }; 

　　　　　　vector<int> a(ia,ia+6);

2) interpolation function

void push_back (const t& x); Adds an element x to the tail of the vector

such as: Vector<string> A (5, "has fun");
A.push_back ("Good luck");
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

Iterator Insert (iterator it,const t& x); Adds an element x before an iterator to an element in a vector

such as: Vector<string> A (5, "has fun");
A.insert (A.begin () +2, "Good luck");
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

Iterator Insert (iterator it,int n,const t& x); Adds n identical elements to an iterator in the vector before it points to the element x

such as: Vector<string> A (5, "has fun");
A.insert (A.begin () +2,2, "Good luck");
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

Iterator Insert (iterator it,const_iterator first,const_iterator last); The data between an iterator in a vector and a [first,last] that inserts another vector of the same type before it points to the element

such as: Vector<string> A (5, "has fun");
Vector<string> B (2, "good luck");
A.insert (A.begin () +2,b.begin (), B.end ());
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

3) Delete function

Iterator Erase (iterator it); The iterator in the delete vector points to the element;

such as: string str[7] = {"Has fun", "has fun", "Good Luck", "Good Luck", "has Fun", "has Fun", "has Fun"};
Vector<string> A (str,str+7);
A.erase (A.begin () +2);
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

Iterator Erase (iterator first,iterator last); Delete the element in [First,last] in the vector, note that last is the next element that points to the final element to be deleted;

such as: string str[7] = {"Has fun", "has fun", "Good Luck", "Good Luck", "has Fun", "has Fun", "has Fun"};
Vector<string> A (str,str+7);
A.erase (A.begin () +2,a.begin () +4);
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

void Pop_back (); Deletes the last element in a vector;

such as: string str[7] = {"Has fun", "has fun", "Good Luck", "Good Luck", "has Fun", "has Fun", "has Fun"};
Vector<string> A (str,str+7);
A.pop_back ();
for (int i=0;i<a.size (); i++)
{
cout<<a[i]<<endl;
}

Program output:

void Clear (); Empties all elements in the vector, functionally equivalent to erase (Vector.begin (), Vector.end ());

4) Traversal function

Reference at (int pos); Returns a reference to the POS location element

Reference Front (); Returns a reference to the first element

Reference back (); Returns a reference to the tail element

Iterator begin (); Returns the vector head pointer, pointing to the first element

Iterator End (); Returns the vector tail pointer, pointing to the next position of the last element of the vector

Reverse_iterator Rbegin (); Reverse iterator, pointing to the last element

Reverse_iterator rend (); A reverse iterator that points to the position before the first element

5) Judgment function

　　BOOL Empty () Const: Determines whether the vector is empty and returns true if NULL

6) Size function

void Resize (size_type n); Adjust the elements of the vector to N, multiple deletions, and a random value

void Resize (size_type n,t& x); Adjust the elements of the vector to N, multiple deletions, and a value of X

void Reserve (Size_type n); Set the storage space allocated to vectors to N, note that you cannot exceed max_size

int size () const; Returns the number of elements in the current vector

int capacity () const; Returns the size of the storage space currently assigned to the vector

int max_size () const; Returns the maximum allowable vector element number value

such as: string str[7] = {"Has fun", "has fun", "Good Luck", "Good Luck", "has Fun", "has Fun", "has Fun"};
Vector<string> A (str,str+7);
A.pop_back ();
Cout<<a.size () <<endl;
Cout<<a.capacity () <<endl;
Cout<<a.max_size () <<endl;

Program output:

7) Other functions

void swap (vector&); Exchange data for two vectors of the same type

void assign (int n,const t& x); Sets the value of the nth element in a vector to X

void Assign (Const_iterator first,const_iterator last); Sets the element in the vector [First,last] to the current vector element

8) Common algorithms

　　Sort by: Sort (A.begin (), A.end ()); The elements of sequence [begin,end] in vector A are arranged from small to large

Inversion: Reverse (A.begin (), A.end ()); The elements of the sequence [begin,end] in vector A are inverted, but not arranged, such as the element in A is 1,3,2,4 and inverted to 4,2,3,1

Copy: Copy (A.begin (), A.end (), B.begin () +1); Copies the elements of the sequence [begin,end] in vector A into B, copying from the position of the B.begin () +1, overwriting the original elements

Find: Find (A.begin (), A.end (), 10); Find 10 in the elements of sequence [begin,end] in vector A, if there is a position to return it in the vector

STL Standard Library of C + + learning notes (iii) vector container