Download presentation
Presentation is loading. Please wait.
Published byMarianna Shields Modified over 9 years ago
1
Lesson 2 McManus COP1006 1
2
Computational ◦ problems involving some kind of mathematical processing Logical ◦ Problems involving relational or logical processing Repetitive ◦ Problems involving repeating a set of mathematical and/or logical instructions. McManusCOP10062
3
The building blocks of equations and expressions ◦ Constants ◦ Variables ◦ Operators ◦ Functions McManusCOP10063
4
A value ◦ a specific alphabetical and/or numeric value ◦ Does not change during the processing of all the instructions in a solution Can be of any data type ◦ Numeric, alphabetical or special symbols Examples ◦ 3, 5, 10, “Mulder”, “Scully”, “+”, “-”, “/” ◦ Note: “” indicates datum rather than variable name McManusCOP10064
5
In some programming languages, constants can be named ◦ Provides protection to the constant value and other areas of the program. ◦ Cannot be changed once given initial value Example ◦ SalesTaxRate = 6 ◦ Commission_Rate = 6 ◦ Note: no spaces within variable names McManusCOP10065
6
May change during processing A name is assigned to each variable used in a solution. ◦ The name references the memory area where the value is stored. May be of any data type Examples ◦ Age, LastName, Address, PayRate McManusCOP10066
7
Use mnemonic terms, that is, the name means something ◦ Use PayRate not Z Do not use spaces ◦ Either combine terms (PayRate) or include an underscore to separate (Pay_Rate) Do not use special symbols Be consistent! ◦ Some languages are case sensitive ◦ PayRate, Pay_Rate, PAYRATE, or PAY_RATE Use appropriate naming convention McManusCOP10067
8
Data ◦ Raw, organized facts Information ◦ Meaningful output McManusCOP10068
9
Most common types ◦ Numeric ◦ Character ◦ Logical Most languages include other data types ◦ Date ◦ Currency ◦ User-defined McManusCOP10069
10
Data TypeData SetExamples IntegerAll whole numbers3456 -43 RealAll real numbers (whole + decimal) 3456.78 0.000123 Character (uses quotation marks) All letters, numbers, and special symbols “A”, “a”, “1”, “5”, “+”, “%” String (uses quotation marks) Combinations of more than one character “Mulder” “Scully” “123-45-6789” LogicalTrue or FalseTrue False McManusCOP100610
11
Include all types of numbers ◦ Integers 3, 5, -5, 0, -1 and 32,767 ◦ Real numbers (floating point numbers) 3.1459, -5745 Scientific Notation 2.3E5 or 5.4E-3, where E stands for the Power of 10 ◦ Can be Positive or Negative McManusCOP100611
12
Alphanumeric data set ◦ Consists of all single-digit numbers, letters, and special characters available to the computer ◦ contained within quotation marks McManusCOP100612
13
EBCDIC – Extended Binary Coded Decimal Information Code ◦ Used on IBM mainframes ASCII - American Standard Code for Information Interchange ◦ 256 characters(1 byte) First 128 – standard Second 128 – specific to computer Unicode(2 bytes) ◦ Replacing ASCII as standard on PC’s McManusCOP100613 See Appendix C
14
Made up of one or more characters. Contained within quotation marks Cannot be used within calculations McManusCOP100614
15
“123” is not the same thing as 123 ◦ The first one is a string ◦ The second one is a number Becomes important when deciding when a piece of data is a string or a number ◦ Ex. Social Security Numbers The first one contains 11 characters and is left aligned whereas the second contains 9 numbers and is right aligned McManusCOP100615
16
The computer’s particular coding scheme (ASCII, Unicode, or EBCDIC) converts the character to its associated ordinal number ◦ Note: Uppercase letters have a smaller ordinal values than lowercase letters “A” = 193 whereas “a” = 129 (Unicode 16-bit) “A” = 65 whereas “a” = 97 (ASCII 8-bit) Once converted, each character, one at a time, can be compared McManusCOP100616
17
Joins character data or string data together Operators: + and & ◦ Dependent on programming language ◦ & can mix data types ◦ + cannot mix data types (also known as Join) Examples ◦ FName & “ ” & MI & “ ” & LName ◦ “James” + “ ” + “T.” + “ ” + “Kirk” = “James T. Kirk” ◦ “James” & “ ” & “T.” & “ ” & “Kirk” = “James T. Kirk” Note the space at the end of the T. McManusCOP100617
18
Consists just two pieces of data ◦ True and False ◦ Different programming languages also allow Yes and No 1 (True) and 0 (False) On and Off McManusCOP100618
19
Dependent on programming language, numerous other pre-defined data types are available. ◦ Examples Dates01/01/1900 January 1, 1900 Times03:35:05 PM15:35:05 Currency3000.00 ◦ Note: This is how the data will be stored, not how it is formatted. McManusCOP100619
20
User-defined Data types ◦ Defined by the user as a new data type Examples Records Employee_Record Fname Lname SSN End McManusCOP100620
21
Programmer designates the data type Data types cannot be mixed ◦ Called data typing All data to be used in calculations must be declared as a numeric data type Each data type uses a data set or domain ◦ Integers – typically -32768 -> 0 -> 32767 but is programming language dependent ◦ Characters – all alphanumeric characters included in the computer’s coding scheme ◦ Logical – the words “true” and “false” McManusCOP100621
22
Small sets of instructions that perform specific tasks and return values. Two types: ◦ Pre-defined Built into a computer language or application. ◦ User-defined McManusCOP100622
23
Benefits ◦ Reduces the amount of code that needs to be written, thus reducing errors of repetition ◦ Shortens the development time ◦ Improves readability McManusCOP100623
24
Data usually placed within parentheses that the function uses without altering the data ◦ In Sqrt(n), the n represents the parameter, in this case a number ◦ In Value(s), the s represents a string McManusCOP100624
25
Mathematical String Conversion Statistical Utility Specific to each programming language…a partial list follows McManusCOP100625
26
McManusCOP100626
27
McManusCOP100627
28
McManusCOP100628
29
McManusCOP100629
30
McManusCOP100630 Error is a special function that appears in most languages and upon execution return control to the program when (not if) system errors occur.
31
The data connectors within expressions and equations. Two types of operations ◦ Unary Negation ◦ Binary Addition, Subtraction, Multiplication, Floating Point Division and Integer Division McManusCOP100631
32
Mathematical ◦ +, -, *, / ◦ \, Mod ◦ ^, and ◦ functions Relational ◦, =, =, <> Logical ◦ And, Or, Not, XOR, EQV McManusCOP100632
33
Integer Division (\) ◦ Regular Floating Point Division, except only the whole number part of the answer is returned. ◦ If given a Floating Point number, the number is rounded—first—before division occurs. Modulo Division (Mod) or Modulus ◦ The remainder part of the answer is returned. McManusCOP100633
34
Returns either the keywords True or False or Returns a non-zero or zero value. ◦ -9, -1, 1, 2 are equivalent to True ◦ 0 is equivalent to False Is stored in two bytes McManusCOP100634
35
Perform comparisons variable - relational operator - variable ◦ Ex. If Y > Z then... ◦ = equal ◦ <> not equal ◦ < less than ◦ > greater than ◦ <= less than or equal to ◦ >= greater than or equal to McManusCOP100635
36
And, Or, XOR, Not, EQV Boolean Expressions are used ◦ To create more complicated Boolean Expressions. ◦ If a = b AND c < d Then … They are defined by using Truth Tables… ◦ Know the significance of each! McManusCOP100636
37
Significance: The only time the result is True is if both A and B are True. McManusCOP100637
38
Significance: The only time the result is False is if both A and B are False. McManusCOP100638
39
Also called the “logical complement” or “logical negation” Significance: Whatever the value of A is, NOT A will be the opposite. McManusCOP100639
40
Significance: The only time the result is True is if A and B are different and False if both A and B are the same. McManusCOP100640
41
Significance: The only time the result is True is if A and B are the same and False if both A and B are the different. McManusCOP100641
42
Data and Operators are combined to form expressions and equations To evaluate these in the proper order, a hierarchy of operations, or Order of Precedence, is used. ◦ Note: Whenever you want to clarify an equation, use the parentheses! McManusCOP100642
43
McManusCOP100643
44
Evaluate the following: A = True, B = False, C = True, D = False A or B or C and D and A and B and (not C) or (not D) To do this, we create what’s called an Evaluation Tree… McManusCOP100644
45
McManusCOP100645 A or B or C and D and A and B and (not C) or (not D) False True False True
46
Expressions ◦ Process the data and the operands, through the use of the operators ◦ Does not store the resultant (answer) ◦ Examples Price * SalesTaxRate (Hours – 40) * Wage * 1.5 Length * Width McManusCOP100646
47
Same as an expression, except the equation stores the resultant (answer) in a memory location “takes on the value of” not equals ◦ Examples SalesTax = Price * SalesTaxRate OvertimePay = (Hours – 40) * Wage * 1.5 Area = Length * Width ◦ SalesTax is the memory location where the answer will be stored Often called Assignment Statements McManusCOP100647
48
Destructive Read-In ◦ The value stored in the variable on the left-hand side of the equals sign is replaced by the result of the expression on the right-hand side. Non-Destructive Read-In ◦ Values used on the right-hand side are protected from being changed. McManusCOP100648 SalesTax = Price * SalesTaxRate D R-I ND R-I ND R-I
49
Algebraic Expressions cannot be represented in the computer. They must be converted to a form the computer will recognize. Thus, Straight Line Form McManusCOP100649 = (X – Y) / ( (X + Y)^2 / (X – Y )^2 ) straight line form
50
McManusCOP100650
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.