C + + Primer Fifth Edition Exercise 13.5

writes a Strvec class
that involves dynamic memory management, memory allocation, FOR_EACH,LAMBDA expressions used in classes, initializing lists, and so on.

#include <bits/stdc++.h> using namespace std; Class Strvec {Public:strvec (): Elements (nullptr), First_free (nullptr), Cap (nullptr) {} Strvec (const initial
        Izer_list<string> &vs) {elements=nullptr;
        First_free=nullptr;
        Cap=nullptr;
    for (auto It:vs) this->push_back (IT);
    } strvec (const strvec&);
    Strvec &operator= (const strvec&);
    ~strvec ();
    void push_back (const string&);
    size_t Size () const {return first_free-elements}
    size_t Capacity () const {return cap-elements;}
    String *begin () const {return elements}
    String *end () const {return First_free}
    void Reserve (const size_t&); void Resize (size_t);//reallocation size, relative to size void Resize (size_t, const string&);//Private:static Allocator<str
    Ing> Alloc;
    void Chk_n_alloc () {if (Size () = Capacity ()) reallocate (); } pair<string*,string*> AlloC_n_copy (const string*,const String *);
    void free ();
    void reallocate ();
    String *elements;
    String *first_free;
String *cap;
};

Allocator<string> Strvec::alloc;
    void Strvec::P ush_back (const string &s) {Chk_n_alloc ();
Alloc.construct (first_free++,s); } pair<string*,string*> strvec::alloc_n_copy (const string *b, const string *e) {Auto data = Alloc.allocate (e-b
    );
Return {data, uninitialized_copy (B,e,data)};
        } void Strvec::free () {if (elements) {//Here is passed to the lambda parameter should be *element rather than element, so it should be destroy (&AMP;P)
        For_each (Elements,first_free,[this] (string &p) {Alloc.destroy (&p);});
        /* for (auto p=first_free;p!=elements;) Alloc.destroy (--P);

    * * Alloc.deallocate (elements,cap-elements);
    } strvec::strvec (const Strvec &s) {Auto NewData = alloc_n_copy (S.begin (), S.end ());
    elements = Newdata.first;
First_free = Cap = Newdata.second; } Strvec::~strvec ()
{free ();} Strvec &strvec::operator= (const Strvec &AMP;RHS) {Auto data = Alloc_n_copy (RHS. Begin (), RHS.
    End ());
    Free ();
    elements = Data.first;
    First_free = Cap = Data.second;
return *this;
    } void Strvec::reallocate () {Auto newcapacity = size ()? 2 * Size (): 1;
    Auto NewData = alloc.allocate (newcapacity)//request twice times memory Auto Dest = Newdata;//alloc return the first pointer auto elem = elements;
    For (size_t i=0;i!=size (); ++i) alloc.construct (Dest++,move (*elem++));
    Free ();
    elements = newdata;//new first pointer first_free = dest;
Cap = elements + newcapacity;
    } void Strvec::reserve (const size_t& len)/reassign size {if (len<=cap-elements)/less than or equal to not apply for return;
    Not-constructed memory reduction auto newcapacity = len;
    Auto NewData = alloc.allocate (newcapacity)//Request Len times memory Auto Dest = Newdata;//alloc return the first pointer auto elem = elements;
    For (size_t i=0;i!=size (); ++i) alloc.construct (Dest++,move (*elem++));
    Free (); elements = newdata;//new First pointer
    First_free = dest;
Cap = elements + newcapacity;
        } void Strvec::resize (size_t n) {if (N>size ())//Reallocate space and initialize construct {if (n>cap-elements)//If it is larger than the length of memory space
        {reserve (n);
            else {string s= ""; 
    while (first_free-elements!=n) {alloc.construct (first_free++,s);//Add construct}}
        } else {while (first_free-elements!=n) {Alloc.destroy (--first_free);//Destroy Construct
    }} void Strvec::resize (size_t n,const string &s) {if (n = size ()) return;
            if (N>size ())//Reallocate space, and initialize the construct {if (n>cap-elements)//if larger than the length of the memory space {Reserve (n);
        For (size_t i=size (); i!=n;++i) alloc.construct (first_free++,s);
        } else {while (first_free-elements!=n) {Alloc.destroy (--first_free);//Destroy Construct
    int main () {Ios::sync_with_stdio (FALSE);
return 0;






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