PASS Week 9/29

REVIEW OF FUNCTIONS




Review the following code and understand the function, the flow of control and when it returns to the caller.

/* This program demonstrates that one function can be
   called multiple times.
   Written by:
   Date:
*/

#include <stdio.h>

// Function Declarations
void printOne (int x);

int main (void)
{
	// Local Declarations
	int a;

	// Statements
	a = 5;                 // First call
	printOne (a);

	a = 33;
	printOne (a);          // Second call

	// Done. Return to operating system.
	return 0;

} // End main

/* =================== printOne ===================
	Print one integer value.
	Pre-call: x contains number to be printed
	Post-call: value in x printed
*/

void printOne (int x)
{
	// Statements
 	printf("%d\n", x);
	return;

} // End printOne


















Problem #1 A thru C

A. Write a program that prompts the user to enter in a value for the base and side of a
   square. Create a variable to hold the area of the square. Compute the area using the
   pow() function in the math.h library. Print out the area of the square with a
   minimum width of 8 and precision of 2 decimal places to the right.

B. Now compose a function to perform the calculation of the area of a square. 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
   declaration in the global are of the source code. Copy or rewrite your processes in a
   function definition under the main function. 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 part #A by adding functions to prompt the user and to
   get the user input and to provide output to the user by taking arguments. Your main
   function should only contain functions calls and a return statement.

NOTE: If you compile this on a Linux machine you must link the math library using the “‐lm”
argument Example: gcc source.c ‐lm


















Problem #2

Write a program that uses functions to compute the perimeter and area of a right triangle
when given the length of the two sides (a and b). Hint: Use three functions, one for
calculating c, a second for the area, and a third for the perimeter.

c^2 = a^2 + b^2
area = .5 * (a * b)
perimeter = a + b + c



















RANDOM NUMBERS


Problem #3

Write a program that generates a random number using a call to the random number
function and prints it to the screen. Call the random number functions several times in the program and see what happens!
Run the program 2‐3 times and observe the results.
Now add the srand() call with the time() argument to add randomness to the numbers. You
ONLY need to call srand() ONCE in the program before the rand() calls.






Problem #4

Create a program that will generate a random set of numbers between 10 and 20 inclusively.

Example:
First, set the range: range = (max value - min value) + 1;
Second, shift to the right: rand() % range + 1; //this starts the counting at 1 instead of zero.




















LOGICAL OPERATOR REVIEw



Examine the following code by compiling it and running it.

/* Demonstrate the results of logical operators.
   Written by:
   Date:
*/

#include <stdio.h>
#include <stdbool.h>

int main (void)
{

	// Local Declarations
	bool a = true;
	bool b = true;
	bool c = false;

	// Statements
	printf(" %2d AND %2d: %2d\n", a, b, a && b);
	printf(" %2d AND %2d: %2d\n", a, c, a && c);
	printf(" %2d AND %2d: %2d\n", c, a, c && a);
	printf(" %2d OR %2d: %2d\n", a, c, a || c);
	printf(" %2d OR %2d: %2d\n", c, a, c || a);
	printf(" %2d OR %2d: %2d\n", c, c, c || c);
	printf("NOT %2d AND NOT %2d: %2d\n", a, c, !a && !c);
	printf("NOT %2d AND %2d: %2d\n", a, c, !a && c);
	printf(" %2d AND NOT %2d: %2d\n", a, c, a && !c);
	return 0;

} // End main

/* Results:
	1 AND 1: ?
	1 AND 0: ?
	0 AND 1: ?
	1 OR 0: ?
	0 OR 1: ?
	0 OR 0: ?
	NOT 1 AND NOT 0: ?
	NOT 1 AND 0: ?
	1 AND NOT 0: ?
*/








Examine the following code by compiling it and running it.

/* Demonstrates the results of relational operators.
   Written by:
   Date:
*/

#include <stdio.h>

int main (void)
{

	// Local Declarations
	int a = 5;
	int b = -3;

	// Statements
	printf(" %2d < %2d is %2d\n", a, b, a < b);
	printf(" %2d == %2d is %2d\n", a, b, a == b);
	printf(" %2d != %2d is %2d\n", a, b, a != b);
	printf(" %2d > %2d is %2d\n", a, b, a > b);
	printf(" %2d <= %2d is %2d\n", a, b, a <= b);
	printf(" %2d >= %2d is %2d\n", a, b, a >= b);
	return 0;

} // main

/* Results:
	5 < -3 is ?
	5 == -3 is ?
	5 != -3 is ?
	5 > -3 is ?
	5 <= -3 is ?
	5 >= -3 is ?
*/