1. More on conditional statements

2. If-else in UML
2018
Risto Heinsar

3. If-else if-else in UML
2018
Risto Heinsar

4. Logical operators Operator Operation Result will be true when … &&
Logical AND
Conjunction
… both sides are true ||
Logical OR
Disjunction
... at least one side is true !
Logical negation
Inversion
... initial condition is false
2018
Risto Heinsar

5. Truth table AND OR NOT a b a && b 1 a b a || b 1 a !a 1 20181 a b
a || b 1 a !a 1
2018
Risto Heinsar

6. Examples if (sorted == 0) if (!sorted)
if (input >= MIN && input <= MAX)
if (input < MIN || input > MAX)
if ((input >= MIN && input <= MAX) ||(ignoreLim == 1))
if (input == 0 || input == 1 || input == 15)
2018
Risto Heinsar

7. De Morgan’s law Useful laws of transformation for Boolean algebra
𝐴∨𝐵 ⟺ 𝐴 ∧ 𝐵
𝐴∧𝐵 ⟺ 𝐴 ∨ 𝐵
Can be extended
The following equations have the same result
The condition is true when the variable value is neither 1 or 2
if (value != 1 && value != 2)
if (!(value == 1 || value == 2))
2018
Risto Heinsar

8. Switch statement Uses an expression instead of a condition
Tries to find a matching case
When no cases match, default case is looked for
If a case matches, it will run all statements until either switch ends or break/continue statement is encountered! This includes other cases below the matching one!
Default case, break and continue statements are optional but usually desired
2018
Risto Heinsar

9. The code switch () if / else if / else switch (expression) {
case constant or expression:
statements
break;
default: }
if (condition) { statements } else if (condition) else
2018
Risto Heinsar

10. Conditionals in UML
2018
Risto Heinsar

11. Examples of switch
switch (value) { case 1: case 2: case 3: printf("Value is either 1, 2 or 3\n"); break; default: printf("Value not identified\n"); }
switch (value) { case 1: printf("Value is 1\n"); break; case 2: printf("Value is 2\n"); default: printf("Value not identified\n"); }
2018
Risto Heinsar

12. Create an algorithm for a program…
… that mimics a typical food scale in the supermarket
Get the weight of the product (from user input)
Get the type of the product (e.g. banana, cucumber, …) (from user input)
Price will be calculated based on the weight and the product type
The cost will be outputted along with the product type
Initially, a menu of possible food items is shown
An error is printed when an unknown product number is chosen.
An error is printed when the cost will calculate to 0
2018
Risto Heinsar

13. Create a product that would emulate a food scale in a supermarket
#include <stdio.h> int main(void) { float weight; int productCode; printf(„Insert the weight of the product\n> „); scanf("%f", weight); switch (productCode) case 0: printf(„Product %d – Banana\n“, select); price = 1.10; break; default: price = 0; } cost = price * weight; printf(„Cost: %f\n“, cost); return 0;
Create a product that would emulate a food scale in a supermarket
5 products (4 of them create by yourself)
Show the list of available products to the user
User must be able to input the product weight and type
Verify that all of the variables needed are declared
Create an exception when cost will be 0
2018
Risto Heinsar