VISUAL C++ PROGRAMMING: CONCEPTS AND PROJECTS Chapter 2A Reading, Processing and Displaying Data (Concepts)

VISUAL C++ PROGRAMMING: CONCEPTS AND PROJECTS

Chapter 2AReading, Processing and Displaying Data (Concepts)

Objectives

Visual C++ Programming

Develop algorithms to solve a problems Learn about the standard C++ data types Declare and initialize variables Read data using the TryParse() method Use the standard C++ arithmetic

operators

Objectives (continued)

Process data using arithmetic expressions

Abbreviate lines of code using shorthand assignment operators

Use the Math::Pow() and Math::Sqrt() methods

Display output using the ToString() method

Solving Problems

An algorithm is an ordered list of steps required to solve a problem

Algorithms are written in pseudocode Algorithms are language independent High-level algorithms provide general list

of tasks Low-level algorithms provide specific

details

Solving Problems (continued)

Data and Data Types

Data includes everything entered into your program (numbers and characters for example)

Data is represented using binary digits called bits

A grouping of eight bits is called a byte Different kinds of data are called data

Data and Data Types (continued)

Primitive data types Boolean (bool) used to represent true or false Character (char) represents a single character

ASCII codes represent char data in one byte Integer (int) includes positive and negative

whole numbers and zero Real numbers (float and double) includes all

values that may have decimal places float – used to represent single precision

numbers double – represents double-precision numbers

Derived data types• Built on primitive types• The String data type is used to represent

text strings• Text strings• Example: “Hello world!”

Variables

• A variable is a named location in memory that stores data

• Variables are created by a process called “declaration”

• When a variable is declared• One or more memory cells are allocated in

memory• The allocated space is assigned a name• The allocated space is associated with a

data type

Variables (continued)

Variables (Continued)

Variable naming conventions• Names must begin with a letter or an

underscore (_) and can only use letters, digits or underscores in the body of the name

• Names are case sensitive (height is not the same name as Height)

• Spaces cannot be used as separators

Initializing Variables

Initialization refers to the act of assigning a value to a variable before it is used

By default, Visual C++ initializes all numeric variables to 0

The programmer can initialize variables using assignment statements

Initializing Variables (continued)

Data Input

Data input refers to the process of reading data into a variable from the program interface

Data is often read in from a TextBox

Data Input (continued)

The TryParse() Method

Parsing is the process of extracting data from a string of text

The TryParse() method parses the Text contained in a TextBox

Every data type class has a built-in TryParse() method

Scope refers to the class or program segment to which something belongs

The scope resolution operator (::) identifies the data type class that TryParse() belongs to

The TryParse() Method (continued)

Parameters are items of information that a method requires

A parameter list is a groups of parameters separated by commas

Data Processing

Computations often involve arithmetic expressions

An arithmetic operator is a symbol that stands for an arithmetic operation

Arithmetic operations are Multiplication (*) Division (/) Mod (%) Addition (+) Subtraction (-)

Arithmetic Operators

Operands are the variables or values that arithmetic operations are performed on

Arithmetic operators are binary (require two operands)

Arithmetic operations are performed from left to right (left to right associative)

Examples: num = num1 + num2; num = num + 1;

Operator Precedence in Arithmetic Expressions

Complex arithmetic expressions have more than one arithmetic operator.

Operator precedence rules dictate which operations are performed first

Multiplication (*), division (/) and mod (%) have higher precedence than addition (+) and subtraction (-)

When two or more operators of the same precedence are in an expression they are performed from left to right

Operator Precedence in Arithmetic Expressions (continued)

Parentheses have higher precedence than all arithmetic operators

Parentheses can be used to perform lower precedence operations before higher ones

Expression trees are used to illustrate the order in which operations are completed when a complex expression is evaluated

Arithmetic Operators and Strings

The addition operator (+) is used to add numeric data

When the operator (+) is used with strings it joins them together (concatenation)

Example: textBox3->Text = textBox1->Text + textBox2->Text;

Shorthand Assignment

Shorthand operators are abbreviations for assignment statements involving arithmetic operations

Shorthand operators: +=, /=, %=, +=, -=

Example: num1 = num1 + num2; is num1 += num2;

The Math Library

The System Math Class contains methods that perform commonly-used tasks

Example: Math::Pow(2,3) Math::Sqrt(45) c = Math::Sqrt(Math::Pow(a,2) + Math:Pow(b,2));

Common Math methods: Exponentiation, Math::Pow() Square Root, Math::Sqrt() Cosine, Math::Cos() Sine, Math::Sin() Tangent, Math::Tan()

Data Output

To display a value in the Text property of a TextBox it must be converted to a String

The ToString() method Example:

textBox3->Text = sum.ToString();

Summary

• Solving problems requires algorithms• Step-by-step lists of instructions

• Commonly used data types are• Bool, char, int, float and double• The String data type stores character strings

• Data is stored in variables• Variable declarations allocate, name and

assign a data type to memory cells• Assignment statements are a common way

to initialize variables

Summary (continued)

• Data Input• Captures the contents of a TextBox and

stores the result in a variable• TryParse()

• Data Processing• Common arithmetic operations (*,/,%,+,-)• Precedence rules (*,/ and % before +,-)• Expression trees are used to evaluate

arithmetic expressions

Summary (continued)

Data Output• Transferring data from a variable to a

TextBox• Use the ToString() method

VISUAL C++ PROGRAMMING: CONCEPTS AND PROJECTS Chapter 2A Reading, Processing and Displaying Data (Concepts)

standard c data typesdeclare

process data

char data

variablesread data

derived data typesbuilt

bytedifferent kinds

zeroreal numbers

program numbers

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