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自定义C++一元多项式类
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?自己定義了一個一元多項式的簡單類，主要是用來實現(xiàn)一個簡單的框架，另外就是驗證編譯器默認(rèn)情況下會為我們的類添加那些構(gòu)造函數(shù)。
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??????????????class?polynomial?{?public:?????polynomial(??);?????polynomial(?float?coeff?[?],int?size?);?????~polynomial(??){}??????void??display(??);?????double?value(float?xx);??????friend?polynomial?operator?+(?const?polynomial&?one,const?polynomial&?two?);?????friend?polynomial?operator?-(?const?polynomial&?one,const?polynomial&?two?);??????private:?????double?power(?float?xx,int?degree?);???????????????private:?????static?const?int?MAXDEGREE=20;?????static?const?float?MINCOEFF=0.000001;?????float?coefficient[?MAXDEGREE+1?];?????int?currentDegree;??};? ?
???#include?"polynomial.h"?#include?<iostream>?#include?<cstdlib>??polynomial::polynomial(??)?{?????for(?int?i=0;i<MAXDEGREE+1;i++?)?????????coefficient[?i?]=0.0;?????currentDegree=0;??????}??polynomial::polynomial(?float?coeff?[??],int?size?)?{????if(?size>MAXDEGREE?)????????{????????????std::cout<<"the?degree?is?bigger?than?the?MAXDEGREE\n";????????????exit(?-1?);????????????????????}????if(?coeff==NULL?)????????{????????????std::cout<<"you?have?input?nothing\n";????????????exit(?-1?);????????????????????}?????for(?int?i=0;i<size;i++?)????????coefficient[?i?]=coeff[?i?];?????currentDegree=size-1;??}??void?polynomial::display(??)?????{?????????std::cout<<"The?MAXDEGREE?=?"<<MAXDEGREE<<"\n";??????????????????std::cout<<coefficient[?0?];?????????for(?int?i=1;i<currentDegree+1;++i?)?????????????{?????????????????if(?(coefficient[?i?]?>?(0.0-MINCOEFF))?&&?(coefficient[?i?]?<MINCOEFF?))?;?????????????????else?????????????????{?????????????????????if(?coefficient[?i?]>0.0?)?????????????????????????std::cout<<"+"<<coefficient[?i?]<<"x^"<<i;?????????????????????else?????????????????????????std::cout<<coefficient[?i?]<<"x^"<<i;?????????????????}?????????????}?????????std::cout<<std::endl;?????}??double?polynomial::power(?float?xx,int?degree?)?????{?????????double?temp=1.0;?????????while(?degree--?)?????????????temp*=xx;?????????return?temp;??????????????}??double?polynomial::value(?float?xx?)?????{?????????double?sum=0.0;?????????for(?int?i=0;i<currentDegree+1;++i?)?????????????{?????????????????sum?=?sum+coefficient[?i?]*power(?xx,i?);??????????????????????????????}?????????return?sum;??????????????}??polynomial?operator?+(?const?polynomial&?one,const?polynomial&?two?)?????{?????????polynomial?temp;??????????????????int?biggerDegree=(?one.currentDegree?>?two.currentDegree??one.currentDegree:two.currentDegree?);?????????for(?int?i=0;i<biggerDegree+1;++i?)?????????????{?????????????????temp.coefficient[?i?]?=?one.coefficient[?i?]+two.coefficient[?i?];??????????????????????????????}?????????temp.currentDegree=biggerDegree;??????????????????return?temp;??????????????}??polynomial?operator?-(?const?polynomial&?one,const?polynomial&?two?)?????{?????????polynomial?temp;??????????????????int?biggerDegree=(?one.currentDegree?>?two.currentDegree??one.currentDegree:two.currentDegree?);?????????for(?int?i=0;i<biggerDegree+1;++i?)?????????????{?????????????????temp.coefficient[?i?]?=?one.coefficient[?i?]-two.coefficient[?i?];??????????????????????????????}?????????temp.currentDegree=biggerDegree;??????????????????return?temp;??????????????}? ?
???#include?<iostream>?#include?"polynomial.h"??int?main(??)?????{?????????float?one[??]={1,2,3,4,5};?????????polynomial?poly_one(?one,5?);?????????poly_one.display(??);?????????std::cout<<?poly_one.value(?1.0?)<<"\n";??????????float?two[??]={1.2,2.5,-3.5,4.5,-5.5};?????????polynomial?poly_two(?two,5?);?????????poly_two.display(??);?????????std::cout<<?poly_two.value(?1.0?)<<"\n";??????????polynomial?poly_three;?????????poly_three=poly_two;?????????poly_three.display(??);??????????polynomial?poly_four(poly_two);?????????poly_four.display(??);???????????????????????????return?0;??????????????}????#include?<iostream>?#include?"polynomial.h"??int?main(??)?????{?????????float?one[??]={1,2,3,4,5};?????????polynomial?poly_one(?one,5?);?????????poly_one.display(??);?????????std::cout<<?poly_one.value(?1.0?)<<"\n";??????????float?two[??]={1.2,2.5,-3.5,4.5,-5.5};?????????polynomial?poly_two(?two,5?);?????????poly_two.display(??);?????????std::cout<<?poly_two.value(?1.0?)<<"\n";??????????polynomial?poly_three;?????????poly_three=poly_two;?????????poly_three.display(??);??????????polynomial?poly_four(poly_two);?????????poly_four.display(??);???????????????????????????return?0;??????????????}? 從main中，poly_three和poly_four可知，如果我們沒有聲明復(fù)制構(gòu)造函數(shù)和賦值構(gòu)造函數(shù)的化，編譯器會為我們自動添加。
另外，如果我們沒有定義類的默認(rèn)構(gòu)造函數(shù)的話，編譯器會為我們添加一個函數(shù)體為空的默認(rèn)構(gòu)造函數(shù)。
還有就是operator =()函數(shù)也會被自動添加，但是只滿足同類對象之間相互賦值。
轉(zhuǎn)載于:https://blog.51cto.com/liuguangtao/537704
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