Going C++

for (int i = 0; i < 10; ++i) {  cout << i << endl;  // i is in scope}cout << i << endl;// ISO standard says i is out of scope// msvc doesn't care [it was a bug in visual c++ 6, it doesn't warn in .net 2003 but can probably be configured to do so]// the version of gcc I tried complained, mentioned the iso standard

#include <string>#include <iostream>int main(void){  std::string myName = "Keith";  std::cout << myName << std::endl;  return 0;}

#include <string>#include <iostream>using namespace std;int main(void){  string myName = "Keith";  cout << myName << endl;  return 0;}

using namespace std;#include <iostream>int main (){   double a = 3.1415927;   double &b = a;                            // b IS a   b = 89;   cout << "a contains: " << a << endl;     // Displays 89.   return 0;}

double x; // declares a variable, allocates space for that variabledouble *p; // declares a pointer, allocates space for the pointervoid foo(double x); // same as above, a function that passes a COPY of the variable, using space on the stack to hold the variable.  This is called Pass-by-value in C.void foop(double *p); // function accepts a pointer to a variable copying the pointer on the stack, not copying the original variable.  This is called pass-by-reference in C.double x2;double *p2;x = x2;  // copies the contents of x2 into x;foo(x2); // copies the contents of x2 into the stack while calling the functionp2 = &x2 // sets the pointer p equal to the address of x2 (& used to be read as the address-of operator in C)foop(&x2); // copies the address of x2 onto the stack while calling the functionp = p2; // copies the value of p2 (which is the address of x2) into pfoop(p2); // copies the value of p2 (address of x2) onto the stack while calling the function*p = x; // copies the value of x, into the thing pointed to by p (p holds the address of x2, so this copies x into x2)

double &r = x; // declares a reference to a double, which allocates space for a pointer, but uses the syntax and operations of a double.  And initialized to refer to the variable x;foor(double &r); // declares a function which copies a reference (pointer) to the item passed in, but uses syntax as if it is not a pointer to manipulate it.r = x2; // copies the contents of x2 into the thing referenced by r (x).foo(r); // copies the contents of the thing pointed to by r (x2) into the stackr = *p2; // copies to contenxt of the thing pointed to by p2 into r.foor(x2); // copies a reference to x2 on the stackfoor(*p2); // copies a reference of the thing pointed to by p2 onto the stack .. .

// assumingdouble x;double &r = x; // declare the referene r to refer to the variable xdouble *p = &x // declare the pointer p to point to the variable x (also - declare the pointer p to be equal to the address of x)// these should pass the same thingfoo(x);foo(r);foo(*p);// these should pass the same thingfoop(&x);foop(&r); // someone double check me here?foop(p);// these should pass the same thingfoor(x);foor(r);foor(*p);