PASS Week 2/10

Examine and discuss the following program (Try running it multiple times and change the value of variable "i"):

#include <stdio.h>

int main(void)
{
	int i = 99;
	printf("The address of i is %p.\n", &i);
	return 0;
}












Structure of a Function in C:
The portion of C code that contains the program of a function is the function definition.
The following illustrates it’s form.

/* You would put your block comment here describing what the function does */

type function_name (parameters with types){
	Local declarations
	Local statements including the return statement.
}












PROBLEM #1 Basic Function

Compose a program that will print the message "A message for you: Have a nice day!"
to the user and then exit returning a 0 to the system on completion. Here is the catch, your
printf() statement DOES NOT go in your main function. Your main function should call
the user-defined function titled "PrintMessage()" with no parameters and
with no return values being used in main. Your user defined function will take
no arguments and return void.

Inside your user function you will use the printf() function to print the following:
"A message for you: Have a nice day!"



/*** SKELETON CODE FOR PROBLEM 1 ***/


#include <stdio.h>

//FUNCTION PROTOTYPE (Declaration) GOES HERE

int main(void){


return 0;
}

//START USER FUNCTION HERE



















PROBLEM #2 Multi‐part program: Pass By Value

A. Write a program that prompts the user to enter in values for the base and
   side of a square, calculates the area of the square, then prints the result to the user.
   Create floating point variables to hold the base, side, and area of the square.
   Then compute the area.
   Print out the area of the square with a minimum width of 8 and
   precision of 2 decimal places to the right.
   (NO USER FUNCTIONS ARE NEEDED FOR THIS PART. JUST PROGRAM IN MAIN)



B. Now modify the program you just made in Part A.
   Compose a function to perform the calculation of the area of a square.
   Use the code from Part A to perform the calculations, and move it inside
   your new function.

   HOW TO STRUCTURE THE FUNCTION:
   First identify the data the function will need to take
   as parameters, and then identify the value if any that would be returned
   from the function. Now create the function prototype (declaration) in the global area of
   the source code. Copy and paste your function prototype under the main function,
   and begin writing the function definition (Refer to Problem 1's structure).

   Test your function by running the program. Does it work with floating point values?
   What changes if any do you need to make to take floating point parameters
   and return a floating point value?



C. Modify the program in problem #1 by adding separate functions for prompting the user,
   getting the user input, and providing output to the user by taking
   arguments. Your main function should only contain functions calls and a
   return statement to return the values to the calling function.

















Problem #3

Compose a program that will compute the hypotenuse of a triangle.
This program uses multiple user-defined functions. Your program should have a
main function, a print instructions function, two get input functions, and a compute hypotenuse function.

The main function should ONLY BE COMPRISED OF FOUR FUNCTION CALL to the functions listed below and
one return statement. Your program must prompt the user to enter in two double type values for the triangle sides.
One function for getting side A and one for getting side B. The program will then use a function to
compute the hypotenuse of a triangle given the two values of sides A and B.

For those who do not recall the equation is the Pythagorean Theorem A^2 + B^2 = C^2.


Create and use the following functions:
   void PrintInstructions( );
   double GetSideA( );
   double GetSideB( );
   void ComputeHypotenuse( );

The challenge here is to know when to call what function and what to do with its return
values. The main function will only contain 2 local statements: a function call (ComputeHypotenuse)
and a return statement (i.e. return 0).



/** SKELETON CODE FOR PROBLEM 3 **/

#include <stdio.h>

//FUNCTION PROTOTYPES GO HERE

int main(void){
 void PrintInstructions( );
 double GetSideA( );
 double GetSideB( );
 ComputeHypotenuse();
 return 0;
}

//PRINT INSTRUCTIONS FUNCTION GOES HERE

//GET SIDE A FUNCTION GOES HERE

//GET SIDE B FUNCTION GOES HERE

//COMPUTER HYPOTENUSE FUNCTION GOES HERE