PHYCS 3730/5720 lab exercise

PHYCS 3730/5730
Lab Exercise

Exercise 1.

Copy file ~p5720/examples/c++broken.cc is C++ code which is quite broken. It is supposed to print out this:

 here is a list of sin(i)/i versus i: 
 sin(1)/i is 0.841471
 sin(2)/i is 0.454649
 sin(3)/i is 0.04704
 sin(4)/i is -0.189201
 sin(5)/i is -0.191785
 sin(6)/i is -0.0465692
 sin(7)/i is 0.0938552
 sin(8)/i is 0.12367
 sin(9)/i is 0.0457909
 sin(10)/i is -0.0544021

but there are several problems. The exercise is to fix them. Things to look out for: curly braces; ending statements with a semicolon; declaring all variables; data types (e.g., int versus double); and the use of "=" versus "==" in conditionals.

Also, when using one of the standard C-math functions (e.g., sin()) it may be in good taste (if not necesary) to

#include

Somethimes it is helpful to put the g++ compiler in maximal whine mode with the -Wall because it can tip you off as to mistakes or potential problems. For example, try

g++ -Wall c++broken.cc

Once you get c++broken.cc into working order, what is the name of the executable code that g++ generates?

Exercise 2.

Compile and run the codes linked below so that you feel comfortable with the following topics:

Getting input from and output to your terminal (standard I/O; c++in_out.cc)
Reading a list of command-line arguments from within your code (c++args.cc)
Reading from and writing to a file (c++fileio.cc and c++fileio2.cc)
Using the standard C math library functions (plus a first random number generator; c++mathfns.cc)
Redirecting standard input and/or output to a file (c++in_redirect.cc and c++out_redirect.cc)

You do not need to modify them, but it may be valuable to do so in order to understand the code.

Exercise 3.

This is an exercise which introduces arrays and pointers. Write a C++ code with the statements:

#include 

using namespace std; // gets us to the standard C++ functions


const int n = 10;  // this is a constant! (not a variable)

int main()
{
   double a[n];
   
   int i;
   for (i = 0; i < n; i++) a[i] = (i+1)*100.0;

   cout << " array elements: \n";
   cout << " a[0]: " << a[0] << endl;
   cout << " a[9]: " << a[9] << endl;
   cout << " a[10]: << a[10] << endl; // ugh!!

   cout << " now, using pointers: \n";
   double* b = a;
   cout << " the pointer itself (address of a[0]): " << b << endl;
   cout << " the value *b: " << *b << endl;

    return 0;
}

Compile and run this code, then add some calls to "cout" to find the values

*(b+1);
b[9];
*++b;

Also, try setting up b, as in

b = &a[??];

so that b[1] has the same value as a[3]. What is the value of b[-1]? How about b[9] in this case?

Finally, try setting a[2] by using *b=-1000.0.

PHYCS 3730/5730 Lab Exercise

Exercise 1.

Exercise 2.

Exercise 3.

PHYCS 3730/5730
Lab Exercise