1. 1 Arithmetic in C

2. 2 Type Casting: STOPPED You can change the data type of the variable in an expression by: (data_Type) Variable_Name Ex: int a = 15; int b = 4; float half; half = a / b; // 3 will be stored in half Q: How to do real division?

3. 3 Increment / Decrement Operators:  ++ Increment operator: int a = 5; a = a + 1; can be written as: a++; or ++a;  -- Decrement Operator: a = a -1; can be written as: a--; or --a;

4. 4 What is a difference? ++a; a++;  Makes no difference if they stand alone!  Makes a difference if used in an expression!  Ex: Given int a, b; a = b = 5; a = 3 * b++; Is equivalent to: a = 3 * b; b++; Outcome: /

5. 5 Cont…  Ex2: a = b = 5; a = 3 * ++b;  Is equivalent to: b++; a = 3 * b; Outcome:

6. 6 Compound Assignment Operators:  Assume: int a = 6;  Increment a by 2: a = a + 2; Using combined assignment operator: +=: a += 2;  Multiply a by 6: a = a * 6; Using combined assignment operator: *=: a *= 6;

7. 7 Cont…  -= a -= b; means: a = a – b;  *= a *= 5; means: a = a * 5;  /= b /= a; means: b = b / a;  %= a %= 2; means: a = a % 2;  a *= (b + c); means: a = a * (b + c);

8. 8 3 major code blocks:  There are 3 main structures / blocks in high level languages: Sequential  What we had so far Selection  Making decisions Repetition  Loops

9. 9 Selection:  Program execution branches to different lines of code based on some condition.  Selection is implemented in C by: if statement switch statement

10. 10 If Statement:  One way decision: Referred to as “Open Branch” in the book. Syntax:Flowchart: if ( condition ) statement(s); Condition? true Statement(s) Rest of the program false

11. 11 Forming conditions in C:  Conditions are formed by comparing 2 things.  You should compare things of similar data type.

12. 12 Relational Operators:  Relational operators are binary operators, i.e. they operate on 2 things.  < less than 5 < 9  <= less than or equal a <= 70  > greater than  >= greater than or equal  == equal to score == 100  != not equal to

13. 13 Relational Expressions (Conditions):  Are any meaningful combination of literals, variables, and relational operators, and arithmetic operators.  Ex: int a = 3, b = 5; 1) a >= 3 2) b == a 3) 12 > 9 4) a >= b 5) a + b * 2 > 10 // true

14. 14 Precedence Rule:  (..)highest  Arithmetic operators  Relational Operatorslowest

15. 15 Compound statement: Ex1: int n = … if (n > 10) printf(“………..”); Ex2: if (n < 10) { printf (“ ……….”); printf (“………...”); } Single statement Compound statement

16. 16 Ex1: check the score, and display a message … int score; printf (“ Enter test score:”); scanf(“%d”, &score); if (score >= 60) { printf (“ You passed the test \n”); printf (“ Good Job! “); } printf (“ Your score is: %d”, score); Q1: What is the output if input is 55? Q2: What is the output for score = 88

17. 17 If / else statement:  Is referred to as “Closed Branch” in the book.  Syntax:Flowchart: if (condition) statement(s); else statement(s); Condition? Statement(s) Rest of the program falsetrue

18. 18  Ex1: Get the user’s age and tell the user if s/he can vote or not. Voting age is 18. int age; printf (“Enter your age: “); scanf (“%d”, &age); if (age >= 18) printf (“ You can vote ”); else printf (“You are too young to vote.”);

19. 19 Exercise:  Write a segment of code that checks the test score. If it is >= 60, display you passed, otherwise, display you failed. int grade; printf(“ Enter the grade: “); scanf(.. )