Lab 4 - Functions

• Display 4.1, page 183 - Using predefined function from cmath
• Display 4.2, page 185 - A list of predefined functions
• Display 4.2, page 191 - Declaring and writing a function
• Display 4.10, page 213 - Declaring and writing a function

1. Write a program that takes the lengths of two sides of a right triangle and outputs the length of the hypotenuse. Remember the Pythagorean theorem states that if a and b are the sides of the triangle and c is the hypotenuse, then the relationship between the three is a2 + b2 = c2. So the length of the hypotenuse is the square root of a2 + b2. This program will use predefined functions from cmath. The output should appear as follows:

   Enter the lengths of the two sides of the triangle: 5 6
   The length of the hypotenuse is 7.81025.
   

   Another example:

   Enter the lengths of the two sides of the triangle: 3 4
   The length of the hypotenuse is 5.
   

2. Take the following code and add the function definition to compute the average of four integers. The function declaration and main function are already complete.

   #include <iostream>
   using namespace std;
   
   // Average takes 4 integers and returns the average
   double average(int a, int b, int c, int d);
   
   int main()
   {
     int a, b, c, d;
     double avg;
   
     cout << "Enter 4 integers: ";
     cin >> a >> b >> c >> d;
     avg = average(a, b, c, d);
     cout << "The average is " << avg << ".\n";
     return 0;
   }
   

   When logged into Helios, you can copy a file containing this code by doing

   cp /usr/users/mdanfor/public_html/cs221-f06/lab4_2.cpp .

   You can also view the file here: lab4_2.cpp