Summary of C + + sequential container learning

C + + sequential container

I. Description of C + + arrays

Dynamic memory allocation for one-dimensional arrays:

Int *num=new Int[len];

Delete []num;

Dynamic memory allocation for two-dimensional arrays:

1, know the second dimension

char (*num) [n];//Pointer to array

num = Newchar[m][n];

Delete[]num;

2, know the first dimension

Char*num [Array of m];//pointers

for (int i=0; i<m; i++)

Num[i] = new Char[n];

for (i=0; i<m; i++)

Delete[]num [i];

Delete[]num;

3, a known one-dimensional allocation of memory (to ensure the continuity of memory)

Char*num [Array of m];//pointers

num [0] = new Char[m*n];

for (int i=1; i<m; i++)

num [i] = num [i-1] + N;

Delete[] a[0];

4, two dimensions are unknown

char** num;

num = new char* [m];//array of assigned pointers

for (int i=0; i<m; i++)

Num[i] = new Char[n];

for (i=0; i<m; i++)

Delete[]num [i];

Delete[]num;

5, two dimensions are unknown, one time to allocate memory (to ensure the continuity of memory)

char * * NUM;

num = new char* [m];

num [0] = new CHAR[M * n];//allocate all space at once

for (int i=1; i<m; i++)

Num[i] = num [i-1] + n;//assigns the array to which each pointer points

delete[]num [0];

Delete[]num;

Ii. C + + container type

Vector Variable size array random access convenience

Deque two-terminal queue random access convenience

List of two-way linked list containers intermediate insertion and deletion is very convenient if there are a lot of small elements extra overhead is very serious

Forward_list one-way linked list container Intermediate Insert Delete very convenient if there are a lot of small elements extra overhead is very serious

Array fixed size arrays

String used to hold strings

Operation of the container:

1. Add elements to the container:

Push_back---Addition of array and forward_list, Push_back adds an element from the tail;

Push_front==list, forward_list, deque containers support Push_forward inserting elements from the beginning;

Intsert-vector, String,list,deque supports insert members, and Forward_list supports special inserts.

The new emplace-Standard introduces three members, and Emplace_front,emplace,emplace_back is a construct rather than a copy element,

2. The operation of accessing elements in the sequential container:

vector<string>c;

C.back ();//Returns a reference to the tail of C, if C is null, the function behavior is undefined;

C.front ();//Returns a reference to the head in C, if C is null, the function behavior is undefined;

C[n];

c.at (n);//Returns a reference with the subscript n, or an exception if the subscript is out of bounds

Note: The at operation is only applicable to the string vector deque array operation; Back is not applicable with forward_list.

3. Delete operation:

Vector <string>c;

C.push_back ();

C.push_front ();

C.erase (P);

C.erase (b,e);

C.clear ();

Note: Member functions that delete elements do not check their parameters and must be guaranteed to exist before they are deleted.

4, (unidirectional linked list) Forward_list Special use {Insert Delete action}

forward_list<int>fist;

Fist.before_begin ()

Fist.cbefore_begin ();

Fist.insert_after ();

Emplace_after ();

Fist.erase_after ();

5. Change the container size

C.resize (n);

C.resize (n,t);

6. member functions for managing capacity

Vector<string> C;

C.shrink_yo_fit); applies to vector string deque only, reducing capacity () to size ().

C.capacity (); How many elements can be stored without reallocating memory

C.reserve (n); Allocates a memory space that can hold at least N.

7. Container Adapter

size_type– a type that is sufficient to hold the maximum value of the current type

value_type-element type

container_type-realization of the underlying type of adaptation

The sample code is as follows:

#include <iostream> #include <string> #include <vector> using namespace Std;int main () {/*//container definition and initialization One container is copied to the other container list<string> str ({"FHT", "HJS", "Hut"}), Vector<const char*> str1 ("A", "B", "BCX");// Copy forward_list<string> Words (Str1.begin (), Str1.end ()); Deque<string> Nu (Str.begin (), it);//Use assign assignment (for sequential containers only) str.assign (Str1.cbegin (), Str1.cend ());// Use swap to exchange two identical containers vector<string> A1 (Ten);vector<string> A2 (A1,A2);//Add elements from the tail string word;vector <string> Contains;while (Cin>>word) {contains.push_back (word);}//Insert element from head list<string> li1;while ( Cin>>word) {Li1.push_front (word);} Insert vector<string> v2;list<string> Li2;li2.insert (Li2.begin (), "Hello") from a specific location in the container; Li2.insert (V2.begin () , "Hello");//vector does not support inserting from the head but can be inserted in this way, but this speed is very slow//forward_list use forward_list<string> fist={ 1,23,4,5,6,6,7,7,8,8,8,665,56,789,6,6,5,5,99,65,78};auto One=fist.before ();//Current Element auto Two=fist.begin (); while ( Curr!=fist.end ()) {if (*curr%2) Curr=fist.erase_after (one); else One=curr;++curr; }*///Manage capacity member functions vector<int> num;cout<< "size () =" <<num.size () <<endl;cout<< "capacity () = "<<num.capacity () <<endl;for (Vector<int>::size_type i=0;i!=40;i++) {num.push_back (i+23);} cout<< "size () New 1=" <<num.size () <<endl;cout<< "Capacity () New 1=" <<num.capacity () < <endl;num.reserve (;cout<<) "size () New 2=" <<num.size () <<endl;cout<< "Capacity () New 2=" < <num.capacity () <<endl;//What happens if you add data? for (int i=0;i<60;i++) num.push_back (67+i) Num.insert (Num.begin (), 12334);cout<< "Add size () =" << Num.size () <<endl;cout<< "add capacity () =" <<num.capacity () <<endl; Return memory allocated out of memory Num.shrink_to_fit ();cout<< "size () =" <<num.size () <<endl;cout<< "after return capacity  () = "<<num.capacity () <<endl; The data in the data cout<< "container in the vector is read:"; for (int i=0;i<num.size (); i++) {cout<<num[i]<< "";} Extra action for string constChar *cp= "Hello world!"; Char nonull[]={' h ', ' I '};string S1 (CP); string S2 (cp,6,20);cout<<s1<< "" <<s2<< "" <<endl ; string S ("Hello world!"); String S3=s.substr (0,7); S.insert (S.size () -2,5, '? '); cout<<s<< "" <<endl;s.erase (S.size () -5,5);cout<<s<< "" <<endl;// Assgin method S.assign (cp,13);cout<<s<< "" <<endl;//append Method S2.append ("Ffh,sbx fy and FY");cout<< s2<< "" <<endl;s2.replace (11,4, "FFH,SBX");cout<<s2<< "" <<endl;//string Search operation string Name ("Anfsdkjhgjs dfngndfmgnd sdghsdfjg"), Nu ("Dhfhj"); auto Posl=name.find ("JS");//All matches cout<<posl<< Endl;auto po=nu.find_first_of (name);//either Match Cout<<po<<endl;system ("pause"); return 0;}

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Summary of C + + sequential container learning