Arithmetic Expressions in C++

CSCE 1062 Outline Data declaration {section 2.3} Arithmetic operators in C++ {section 2.6} Mixed data type arithmetic in C++ Arithmetic expressions in C++ Operators’ precedence Arithmetic expressions’ evaluation examples

CSCE 1063 Data Declaration Remember the memory anatomy? It is much easier to set aside memory with names (identifiers). Thus the declaration statements are used to set aside memory with a specific name for the data and define its values and operations. type identifier-list; Examples: char response; char c, grade = ‘A’; int minElement; int n, j = 1; float score; float x, y, z = 40.0; bool flag; The value can change during execution H AddressContents ADD 7 3 x n c

CSCE 1064 Data Declaration (cont’d) When variables are declared 1.Memory allocated for value of specified type 2.Variable name associated with that memory location 3.Memory initialized with values provided (if any) 27

CSCE 1065 Constant Declarations A constant is a memory cell whose value cannot change during execution once it is set in the declartion. const type constant-identifier = value; E.g.: const float KM_PER_MILE = 1.609; It is a good C++ programming practice to capitalize all letters for constant names. Any data type (e.g. int, float, char, or bool) could be declared as constant.

CSCE 1066 Identifiers A valid identifier (variable or function name) must consist of letters, digits, or underscore only. A valid identifier must not begin with a digit. Valid identifiers: letter, letter1, _letter Invalid identifiers: 1letter, float, hell o You cannot use a C++ reserved word as an identifier. Always try to associate meaningful identifiers. It is a good C++ programming practice to capitalize the first letter of each word (after the first) when using multiple word identifiers Remember that C++ is case sensitive ( cost != Cost )

CSCE 1067 Arithmetic Operators in C++ +Addition - Subtraction *Multiplication /Division % Modulus (remainder operator, only for integers) Examples of integer modulus: 7 % 2 = % 100 = % 5 = 4 15 % 0 undefined Examples of integer division (result is integer): 15 / 3 = 5 15 / 2 = 7 0 / 15 = 0 15 / 0 undefined

CSCE 1068 Mixed Data Type Arithmetic in C++ Example: 4.6 / 2 evaluates to 2.3 Rule: when an integer and a floating point operand are combined by an operator, the integer gets converted to the floating point type.

CSCE 1069 Arithmetic Expressions in C++ An assignment statement has the following format: variable = expression; e.g.: kms = KM_PER_MILE * miles;  The arithmetic expression to the right of the assignment operator (=) gets evaluated first  Then the result is stored in the variable on the left side of the assignment operator

CSCE Arithmetic Expressions in C++ (cont’d) Mixed-type assignments:  If the variable on left side of assignment is of different type than the type of the evaluated expression on the right side of =, the result of the expression must be converted to the appropriate type.  Examples: float a, b, x; int m, n; a = 10;// result is 10.0 stored in a b = 3.5; m = 5; n = 10; x = m / n;// result is 0 assigned to x; therefore x is 0.0 m = b * 3;// result is 10 assigned to m

CSCE Arithmetic Expressions in C++ (cont ’ d) What if the arithmetic expression contains more than one operator? x = z - (a + b / 2) + w * -y; How many operators do we have in the above expression? Computers follow operator precedence rules to evaluate expressions.  The formula: m = y - b x - a  The computer equivalent is: m = (y - b) / (x - a); Must use ( ) because of operator precedence.

CSCE Order of Operator Precedence ( )nested expressions evaluated inside out unary +, - *, /, % If there are several, then evaluate from left-to-right binary +, - If there are several, then evaluate from left-to-right = Highest Lowest Associativity Warning: watch out for the types of operands and the type of the result from evaluating each operation!

CSCE Example 1 x = z - (a + b / 2) + w * -y; x integer z ab wy (3 + 9 / 2) + 2 * / 4 + x = 8 - (3 + 9 / 2) + 2 * / 2 (3 + 4 ) * * * 10 +

CSCE Example 2 m = x + k / 2; m integer x k / 2 convert to float convert to int / 2

CSCE Next lecture will be about Library Functions