- int argc ，char * argv[] - argument count & argument vector
argc - 命令行参数个数，argv[]依次指向每一个命令行参数，其中argv[0]为程序名字：下面的程序包含了完整的程序路径。
#include
int main(int argc, char *argv[]){ int i = 0; // begin with 0 while (i < argc) std::cout << argv[i++] // output string << " " // output SPACE << std::endl; // terminate output line return 0;} - 引用
1）作为返回值，不需要产生临时对象，然后拷贝这个对象，（见下面代码的注释），目前不要深究引用机制，目前记住的返回引用的场景：输入流、 //发现其他的再补充
2）引用类型参数#include
using namespace std;int & rfun(int &); //don't dig more,ref func saves time.int fun(int);void main(void) { int a = 7, b = 9; int &ra = a, &rb = b; //Treat ra as another name of a int *pa = &ra, *pb = &rb; cout << pa << " " << (void *)pa << endl; cout << pb << " " << (void *)pb << endl; cout << a << " " << b << endl; cout << rb << " " << (void *)&rb << endl; //&rb == pb always. rb = rfun(ra); //b=ra; rb=ra; --> int &rd=a; //rb=fun(ra); cout << rb << " " << (void *)&rb << endl; cout << a << " " << b << endl; rb = 8; cout << a << " " << b << endl;}int & rfun(int & r) { return r; // b=fun(a) --> b=a;};int fun(int r) { return r; // b=fun(a) --> r=a; b=r;}; 对于class，vector等类型的参数，引用 避免了值拷贝，提升效率，使用引用，函数可以改变实参的值，如果在调用过程中实参值不会发生变化，那么添加 const 修饰。
//call by ref can change the value after func called.#includeusing namespace std;void funr(const int &, int);int& rfun(const int &, int);void main(void) { int a = 100; int& b = a; const int& c = 20; const int & ca = a; a = 200; const int cb = 300; cout << &a << " " << a << endl; cout << &b << " " << b << endl; cout << &c << " " << c << endl; cout << endl << endl; funr(a, a); //first a,like above;second a, int tmp = a; funr(2, 2); cout << endl << endl; int& rf = rfun(c, c); cout << &rf << " " << rf << endl;}void funr(const int & ra, int pa) { cout << &ra << " " << ra << endl; cout << &pa << " " << pa << endl; //int tmp = pa, &pa is addr of tmp}int& rfun(const int & ra, int pa) { // b = rfun(ra,pa)-->b = ra int x = 200, &d = x; cout << &ra << " " << ra << endl; cout << &pa << " " << pa << endl; return (int&)ra;}
以上则是目前想到的关于引用的知识点小结，以前曾经写过这话题的博文，今天讲解细致些，看注释，运行程序，更快速理解引用，VS2015社区版。
2016-5-21补充代码如下：
#includeusing namespace std;class A {public: int a; A(int = 0); A(const A &); A& operator = (const A &); void PV(A); void PR(A&); A RV(void); A& RR(void);}; // AA::A(int x) : a(x) { cout << "Constructor (value)" << endl; }A::A(const A & x) { cout << "Constructor (copy)-" << (void *)&x << endl; a = x.a; }A& A::operator = (const A & x) { cout << "Operator (=) @ " << (void *)&x << endl; a = x.a; return *this; }void A::PV(A x) { cout << "Calling By Value @ " << (void *)&x << endl; }void A::PR(A &x) { cout << "Calling By Refe. @ " << (void *)&x << endl; }A A::RV(void) { cout << "Calling Rt Value" << endl; return *this; }A& A::RR(void) { cout << "Calling Rt Refe." << endl; return *this; }int main(void) { A oa, ob(3); cout << "oa @ " << (void *)&oa << endl; cout << "ob @ " << (void *)&ob << endl; cout << endl << "00000000000000000000000000000" << endl; oa.PR(ob); cout << endl << "11111111111111111111111111111" << endl; oa.PV(ob); cout << endl << "22222222222222222222222222222" << endl; ob = oa.RR(); cout << endl << "33333333333333333333333333333" << endl; ob = oa.RV(); cout << endl << "44444444444444444444444444444" << endl; return 0;}
参数类型为class且为值传递的时，先调用对象的拷贝构造函数生成中间值，然后传入这个中间值到函数中；返回类型为值类型的时，会调用拷贝构造函数生成中间值，实际上返回的是这个中间值。