1. EECE.2160 ECE Application Programming
Instructors:
Dr. Michael Geiger
Fall 2018
Lecture 9:
Range checking with if statements

2. Announcements/reminders
Grader: Pakin Pongcheewin
Hours: W/F 2-6 (please contact by first)
Program 1 resubmissions due Wed, 9/26
You must Dr. Geiger and Pakin when you resubmit
Program 2 due today
Program 3 due Monday, 10/1
Looking ahead: Exam 1 on Friday, 10/5
Will be allowed one double-sided 8.5” x 11” note sheet
No calculators or other electronic devices allowed
5/25/2019
ECE Application Programming: Lecture 9

3. ECE Application Programming: Lecture 9
Lecture outline
Review
If statements
Today’s lecture
Program 3 intro
Range checking with if statements
5/25/2019
ECE Application Programming: Lecture 9

4. Program 3: bitwise operators
Basic 1-bit Boolean calculator
1-bit values = 0 or 1
Boolean operations: bitwise logical operations
& (AND), | (OR), ^ (XOR)
Not the same as &&, || used to combine conditions
Bitwise operators are binary operators
Given unsigned x = 1; unsigned y = 0;
printf("x | y = %u, x & y = %u, x ^ y = %u\n", x | y, x & y, x ^ y); would print
x | y = 1, x & y = 0, x ^ y = 1
5/25/2019
ECE Application Programming: Lecture 9

5. Bitwise Logical Operations
AND A B
A&B 1
NOT (not needed for P3) A
~ A 1 OR
XOR (exclusive or) A B
A|B 1 A B
A^B 1
5/25/2019
ECE Application Programming: Lecture 9

6. Program 3: conditional statements
Conditional statements will be required to
Check for errors
Evaluate which operator user entered
Don’t use conditional statements to evaluate bitwise operations!
You don’t need to directly implement truth tables
Operators will do that work for you
5/25/2019
ECE Application Programming: Lecture 9

7. ECE Application Programming: Lecture 9
Review: if statements
Conditional execution using if statements:
Form:
if (<expression>)
<statement>
[ else brackets show
<statement> ] else is optional
Expression frequently uses relational operators to test equality/inequality
< > <= >= == !=
e.g., if (x <= 5)
Can combine conditions using logical operators
AND : && OR: ||
e.g., if ((x <= 5) && (x > 0))
Can test if condition is false using logical NOT: !
e.g., if (!(x < 5))
5/25/2019
ECE Application Programming: Lecture 9

8. if (range checking - take 1)
int n;
printf("Enter a number 1 to 10: "); scanf("%d",&n); if (n > 10) { printf(“That’s not in range!"); } else if (n < 1) { printf(“That’s not in range!"); } else { printf("Good job!"); }
5/25/2019
ECE Application Programming: Lecture 9

9. if (range checking - take 2)
If there is only one statement needed for the true and/or false condition, the {} are not needed
int n;
printf("Enter a number 1 to 10: "); scanf("%d",&n); if (n > 10) printf(“That’s not in range!"); else if (n < 1) printf(“That’s not in range!"); else printf("Good job!");
5/25/2019
ECE Application Programming: Lecture 9

10. if (range checking - take 3)
Use the && or || as needed to check for multiple conditions
int n;
printf("Enter a number 1 to 10: "); scanf("%d",&n);
if ( (n > 10) || (n < 1) ) printf(“That’s not in range!"); else printf("Good job!");
5/25/2019
ECE Application Programming: Lecture 9

11. if (range checking - take 4)
Use the && or || as needed to check for multiple conditions
int n;
printf("Enter a number 1 to 10: "); scanf("%d",&n);
if ( (1 <= n) && (n <= 10) ) printf(“Good job!"); else printf(“That’s not in range!");
5/25/2019
ECE Application Programming: Lecture 9

12. if (range checking) (The WRONG WAY)
int n;
printf("Enter a number 1 to 10: "); scanf("%d",&n);
if (1 <= n <= 10 ) // THIS MAY NOT COMPILE printf("Good job!"); else printf(“That’s not in range!");
5/25/2019
ECE Application Programming: Lecture 9

13. Example: if statements
Write a short code sequence to do each of the following:
Given int x, check its value
If x is greater than 5 and less than or equal to 10, print x
Prompt for and read temperature as input (type double)
If temp is 90 or higher, print “It’s too hot!”
If temp is 32 or lower, print “It’s freezing!”
In all other cases, print “It’s okay”
Read 3 int values and print error if input problem
If fewer than 3 values read, print error message with number of values
Example: Error: only 2 inputs read correctly
5/25/2019
ECE Application Programming: Lecture 9

14. ECE Application Programming: Lecture 9
Example solution
Given int x, check its value
If x is greater than 5 and less than or equal to 10, print x
if ((x > 5) && (x <= 10))
printf(“%d\n”, x);
5/25/2019
ECE Application Programming: Lecture 9

15. Example solution (cont.)
Prompt for and read temperature as input (type double)
If temp is 90 or higher, print “It’s too hot!”
If temp is 32 or lower, print “It’s freezing!”
In all other cases, print “It’s okay”
int main() {
double temp;
printf(“Enter temperature: “);
scanf(“%lf”, &temp);
if (temp >= 90)
printf(“It’s too hot!\n”);
else if (temp <= 32)
printf(“It’s too cold!\n”);
else
printf(“It’s okay\n”);
return 0; }
5/25/2019
ECE Application Programming: Lecture 9

16. Example solution (cont.)
Read 3 int values and print error if input problem
If fewer than 3 values read, print error message with number of values
Example: Error: only 2 inputs read correctly
int main() {
int x, y, z; // Input values
int num; // # values read
num = scanf(“%d %d %d”, &x, &y, &z);
if (num < 3)
printf(“Error: only %d inputs read correctly”,
num);
return 0; }
5/25/2019
ECE Application Programming: Lecture 9

17. ECE Application Programming: Lecture 9
Final notes
Next time
Switch statements
While loops
Reminders:
Grader: Pakin Pongcheewin
Hours: W/F 2-6 (please contact by first)
Program 1 resubmissions due Wed, 9/26
You must Dr. Geiger and Pakin when you resubmit
Program 2 due today
Program 3 due Monday, 10/1
Looking ahead: Exam 1 on Friday, 10/5
Will be allowed one double-sided 8.5” x 11” note sheet
No calculators or other electronic devices allowed
5/25/2019
ECE Application Programming: Lecture 9