C++ Sample Program

Today will be the first evening for an engineering class... I've already previewed tonight's lecture material that includes some sample C++ code.

I took C++ ~10 years ago.   Haven't used it since and am very rusty.   I still have Borland's C++ v5.02 compiler.   When plugging the teacher's code in the "old" compiler, none of them work.

Obviously, I'll get more info tonight.   I was wondering if someone already could tell me what I'm missing.  Has the language since and I could not use v5.02 for the suggested code?    Are the progams (between ***s below) all separate sample program?  

EEH


Sample Code
==========

// pe02-01.cpp
#include <iostream>
using namespace std;

int main()
{
  cout << "Replace this with your code.\n";
  return 0;

}

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// yourcat.cpp -- input and output
#include <iostream>
using namespace std;
int main()
{
    int fleas;

    cout << "How many fleas does your cat have?\n";
    cin >> fleas;               // C++ input
// next line concatenates output
    cout << "Well, that's " << fleas << " fleas too many!\n";

    return 0;
}

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// sqrt.cpp -- use a square root function
#include <iostream>
using namespace std;
#include <cmath>        // or math.h
int main()
{
    double cover, side;       // use double for real numbers
    cout << "How many square feet .. do you have?\n";
    cin >> cover;
    side = sqrt(cover); // call function, assign return value
    cout << "Your square has sides of " << side;
    cout << " feet << \n";
    return 0;
}

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// forloop.cpp -- introducing the for loop
#include <iostream>
using namespace std;
int main()
{
    int i;  // create a counter
    //   initialize; test ; update
    for (int i = 0; i < 5; i++)
      {
        cout << "C++ knows loops.\n";
      } //Use braces if >1 statement
    cout << "C++ knows when to stop.\n";
    return 0;
}

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// uniform random number generator
#include <iostream>
#include <cmath>
using namespace std;
//function prototypes (if any)


int main()
{
//  initializations
const int N=1024 ;
int  i, tst;
float r, avg, x2, sum, var ;
r = 0.0 ;
tst = 1 ;
while (tst >= 0 ) // while loop
      {
      cout << "continue?  ;
      cin >> tst;
//test for termination condition
      if (tst >= 0)


{
      float max = pow(2.0,15.0); // math fcn.
      max=max-1; // want 2 **15 - 1
      cout<< "\n";
      avg=0;
      x2=0;
      sum=0;
      int init=-1;
      for ( i=0; i<N;  i++ )
            {      
            r = rand() / max; // normalize {0-1}
            x2=x2 + r*r; // accum. xi^2 and xi
             sum = sum + r;
            } // end for


//  compute sample variance and average
      
      var = ( N * x2 - sum*sum ) / ( N *( N-1) );
      cout << "average =  < sum / N << "Sample   var. =  << var << "\n";
      
    }// end if
}// end while
return(0); /*end */
}
//   end Example

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