c++ 学习资料

swap

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#include <iostream>
#include <vector>
using namespace std;

int swap1(int* px,int* py){
int z=*px;
*px=*py;
*py=z;
return 0;
}

int swap2(int &ix,int &iy){
int z=ix;
ix=iy;
iy=z;
return 0;
}

int main(int argc, char* argv[])
{
int x,y;
cout<<"intput x and y:"<<endl;

cin>>x;
cin>>y;
swap1(&x,&y);
cout<<"swap1:"<<x<<","<<y<<endl;
swap2(x,y);
cout<<"swap2:"<<x<<","<<y<<endl;
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}

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seq

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#include <iostream>
#include <vector>
using namespace std;

bool fibon_elem(int iPos, int &iElem)
{
??? int n2 = 1, n1 = 1;
??? if (iPos <= 0 || iPos >= 1024)
??? {
??????? iElem = 0; return false;
??? }
??? iElem = 1;
??? for (int iX = 3; iX <= iPos; iX++)
??? {
??????? iElem = n2 + n1;
??????? n2 = n1;
??????? n1 = iElem;
??? }
??? return true;
}

int fibon_elem(int iPos)
{
??? int n2 = 1, n1 = 1;
??? int iElem = 1;
???
??? for (int iX = 3; iX <= iPos; iX++)
??? {
??????? iElem = n2 + n1;
??????? n2 = n1;
??????? n1 = iElem;
??? }
??? return iElem;
}

vector<int> fibon_seq(int iLength)
{
? if (iLength <= 0 || iLength >= 1024)
??? {
??????? cerr <<"Length"<<iLength<<"not supported, reset to 8"<<endl;
??????? iLength = 8;
??? }
??? vector<int> Elems( iLength );
??? for (int iX = 0; iX < iLength; iX++){
??????? if (iX == 0 || iX == 1)
??????? {
??????????? Elems[iX] = 1;
??????? }
??????? else
??????? {
??????????? Elems[iX] = Elems[iX-1] + Elems[iX-2];
??????? }
??? }
??? return Elems;
}

int main(int argc, char* argv[])
{
?int x,y;
?cout<<"please input a num(from 0-1024):";
?cin>>x;
?cout<<"first result:"<<fibon_elem(x);
?if(fibon_elem(x,y))
??cout<<endl<<"second result:"<<y;
?else
??cout<<endl<<"second result:error";
?vector<int> Elems=fibon_seq(x);
?cout<<endl<<"third result:";
?for(int i=0;i<Elems.size();i++)
??cout<<Elems[i]<<",";
?cout<<endl;
?return 0;
}

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--------------------------------------------

根据main的参数选择函数

int main(int argc, char* argv[])
{
?if(argc!=2){
? cout<<"input error,like guo1.exe c/e"<<endl;
? return 0;
?}

?if(strcmp(argv[1],"c")==0)
??cout<<"c";
?else
??cout<<"e";
?
}

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类

-----------------------

#include <iostream>
#include <vector>
using namespace std;

class X
{
public:
?? int mf1(){cout<<"hello";return 0;};
????? int mf2() {? return mf3();? }
private:
????? int mf3(){cout<<"hello";return 0;};
????
} x;

void main()
{
???? x.mf1();? //yes
???? x.mf2();
? //x.mf3();? //Error! Private member can’t be accessed out of the class
}

?

---------------y

#include <iostream>
#include <vector>
using namespace std;

class Y
{
public:
????? int _m1;
????? int get_m2() { return _m2;}
????? void set_m2(int x) { _m2 = x;}
private:
????? int _m2;???
} y;

void main()
{
???? y._m1++;? //Not suggested! Direct access data members
? cout<<y._m1;
???? y.set_m2(1);? //Suggested! The data member is accessed under control
? cout<<y.get_m2();
}