review of c++

1.

const rational operator*(const rational& lhs,const rational& rhs)
　　{
　　　　return rational(lhs.numerator() * rhs.numerator(),
　　　　lhs.denominator() * rhs.denominator());
　　}
　　rational onefourth（1,4）；
　　rational result;
　　result = onefourth * 2; // 工作良好
　　result = 2 * onefourth; // 万岁，它也工作了！

We do not need to use friend function, it would bring more troubles than help to you.

In terms of friend function:

if this operator becomes String's member function, it should be this shape: Sting>>cin;

thus, we can only use friend function here.

istream& operator>>(istream& input,string& string)
　　{
　　　　delete [] string.data;
　　　　read from input into some memory,and make string.data
　　　　point to it
　　　　return input;
　　}
ostream& operator<<(ostream& output,const string& string)
　　{
　　　　return output << string.data;
　　}

const int ival = 1024;
      const int &refVal = ival;      // ok: both reference and object are const
      int &ref2 = ival;              // error: non const reference to a const object

1. new and delete must appear in pair

2. use new to allocate memory.

the most useful place we can utilize it: dynamic array

(caveat: we cannot use sizeof() to figure out the number of elements. Only can we program by ourselves to track the number )

reference:

http://baike.baidu.com/view/534170.htm

=========================================================

Rome wasn't built in a day.

Finished the basic review of the fundament of c++.

Written out npv function.

Need to make a detailed plan of buliding the system.

(c++, python, excel, sas...) only these can be involved in.

That's to say I have to adjourn my fucking web development.

really wish to find several partners in HKUST.
原文链接: https://www.cnblogs.com/surgod/archive/2012/09/21/2697509.html

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