C++函数与指针
导读:收集整理的这篇文章主要介绍了C++函数与指针,觉得挺不错的,现在分享给大家,也给大家做个参考。最近在看C++ PRimer plus,感觉函数与指针这一章难点比较多,记写笔记,加强理解.From C++ Primer Plus: Chapt...
收集整理的这篇文章主要介绍了C++函数与指针,觉得挺不错的,现在分享给大家,也给大家做个参考。最近在看C++ PRimer plus,感觉函数与指针这一章难点比较多,记写笔记,加强理解.From C++ Primer Plus: Chapter 7 Function:C++ Programming Modules
1. 如何声明函数指针?
和函数原型类似: 需要声明指针指向函数的返回值和参数列表
double PAM(int); //参数为int 类型,返回值为double 类型的函数double (*pf); (int) //指向参数为int类型,返回值为double 类型的指针pf = pam; //函数名代表了函数的地址double x = pam(4); //函数名调用double x = (*pf)(4); //指针调用double x = pf(4); //C++也允许将指针名当作函数名使用
2. C++ 11 自动类型推断
const double * F1(const double *, int); const double * (*p1)(const double *, int); //p1 poITns to f1 auto p2 = f1; //C++11 automatic tyPE deduction,p2 points to f1 as well
3. 将指针名当作函数名使用
//前面函数为double *类型,cout第一部分返回double指针,第二部分返回double指针指向的值cout(*p1)(av,3)":"*(*p1)(av,3)endl; //和上面的cout一样只不过是使用函数指针名来调用函数coutp2(av,3)":"*p2(av,3)endl;
4. 函数指针数组
const double *(*pa[3]) (const double *,int) = { f1,f2,f3} ; //创建函数指针数组//通过指针调用函数,得到返回的指针const double *px = pa[0](av,3); //call by pointer as if it were a function nameconst double *py = (*pa[0])(av,3); //正常调用//得到函数返回指针指向的值double x = *pa[0](av,3); double x = *(*pa[0])(av,3);
5. 指向指针数组的指针
指针数组和数组指针的区别
*pd[3] //an array of 3 pointers(*pd)[3] //a pointer to an array of three elements
指向数组的指针
1 auto pc = & pa; //& pa是整个数组的地址, pa是数组第一个元素首地址
2
3 const double * (*(*pd)[3])(const double *, int ) = & pa; //和第一个等价
4
5 **& pa = *pa = pa[0]
代码:
//arfupt.cpp -- an array of function pointers#includeiostream> //VARious notations,same signaturesconst double *f1(const double ar[],int n); const double *f2(const double [],int); const double *f3(const double *,int); int main(){ using namespace std; double av[3] = { 1112.3,1542.6,2227.9} ; //pointer to a function const double *(*p1)(const double *,int) = f1; auto p2 = f2; //C++ 11 utomatic type deduction //pre-C++11 can use the following code instead //const double *(*p2)(const double *,int) = f2; cout"Using pointers to functions:\n"; cout"Address Value\n"; cout(*p1)(av,3)":"*(*p1)(av,3)endl; coutp2(av,3)":"*p2(av,3)endl; //pa an array of pointers //auto doesn't work with list initialization const double *(*pa[3])(const double *,int) = { f1,f2,f3} ; //pb a pointer to First element of pa auto pb = pa; // pre-C++11 can use the following code instead // const double *(**pb)(const double *, int) = pa; cout"\nUsing an array of pointers to functions:\n"; cout"Address Value\n"; for(int i = 0; i 3; i++) coutpa[i](av,3)":"*pa[i](av,3)endl; cout"\nUsing a pointer to a pointer to a function:\n"; cout"Address Value\n"; for(int i = 0; i 3; i++) coutpb[i](av,3)":"*pb[i](av,3)endl; //what about a pointer to an array of function pointers cout"\nUsing pointers to an array of pointers:\n"; cout"Address Value\n"; //easy way to declare pc auto pc = & pa; // pre-C++11 can use the following code instead // const double *(*(*pc)[3])(const double *, int) = & pa; cout(*pc)[0](av,3)":"*(*pc)[0](av,3)endl; //hard way to declare pd const double *(*(*pd)[3])(const double *,int) = & pa; //Store return value in pdb const double *pdb = (*pd)[1](av,3); coutpdb":"*pdbendl; //alternative notation cout(*(pd)[2])(av,3)":"*(*(*pd)[2])(av,3)endl; } const double * f1(const double * ar, int n){ return ar; } const double * f2(const double ar[], int n){ return ar+1; } const double * f3(const double ar[], int n){ return ar+2; }
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