mistake in tutorial re: stl vector

in the tutorial at cprogramming.com (this site) on stl vectors it states:

Quote:

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Vectors are more powerful than arrays because the number of functions that are available for accessing and modifying vectors. Unfortunately, the [] operator still does not provide bounds checking. Let's take a look at several functions provided by the vector class:

Code:

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unsigned int size();            Returns the number of elements in a vector
push_back(TYPE element);        Adds an element to the end of a vector
swap(int x, int y);            Swap elements x and y
bool empty();                  Returns true if the vector is empty
void clear();                  Erase all elements of the vector

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...

Quote:

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Code:

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int main()
{
  vector <int> example;        //Vector to store integers
  example.push_back(3);        //Add 3 onto the vector
  example.push_back(10);        //Add 10 to the end
  example.push_back(33);        //Add 33 to the end
  for(int x=0; x<example.size(); x++)
  cout<<example[x]<<" ";        //Should output: 3 10 33
  if(!example.empty())          //Checks if empty
  example.clear();              //Clears vector
  vector <int> another_vector;  //Creates another vector to store integers
  another_vector.push_back(10); //Adds to end of vector
  example.push_back(10);        //Same
  if(example==another_vector)  //To show testing equality
  example.push_back(20);
  example.switch(1, 2);        //Switches elements 1 and 2
  for(int y=0; y<example.size(); y++)
  cout<<example[y]<<" ";        //Should output 20 10
  return 0;
}

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the above is clipped from this page


is switch really a vector class function? i get errors because i think it's mistaking it as the keyword switch.
is there some kind of swap function in vector arrays? if so, what's its syntax?

I believe the function is swap.

>is switch really a vector class function?
No, switch is a reserved keyword. The vector class does have a swap method, but it doesn't swap two elements in a vector, it swaps the entire contents of two vectors. If you want to swap two individual elements in one vector, use the swap method in <algorithm>.

Code:

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#include <algorithm>
#include <iostream>
#include <vector>

int main ( void )
{
  std::vector<int> v;
  v.push_back ( 0 );
  v.push_back ( 1 );
  std::cout<<"v[0]: "<< v[0] <<"\n"<<"v[1]: "<< v[1] <<"\n";
  std::swap ( v[0], v[1] );
  std::cout<<"v[0]: "<< v[0] <<"\n"<<"v[1]: "<< v[1] <<"\n";
  return 0;
}

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-Prelude

continuing on stl:
is there algorithm function that can sort by a property of an object?

ie:
i understand sort to be like this:
vector <int> vec_class;
//push a bunch of stuff into vec_class
sort (vec_class.begin(),vec_class.end());

it sorts each vec_class int so that they line up numerically
is there a way to make it sort by the property without resorting to a specialized function?
vector<some_object* > vec_class;
//push a bunch of object pointers, each having memory allocated to it
vec_class[4]->property=3; //property is an int
vec_class[2]->property=8;
//etc...

//sort array by value of each property

You would have to overload operator< for some_object. Make that compare whichever property you want.