C++ Programming Language Basics

C++ Programming Language Basics

• Computer programs are generally divided into header (global) and main sections
• The header section contains comments explaining the program and which libraries it uses.
• Comments are ignored by the compiler but are useful for programmers to understand and maintain the program.
• Comments start with // for single line comments, or /* and */ for multi-line comments.
• The main section specifies the instructions the computer will directly execute.

Memory

• Memory storage holds instructions and data used by the program temporarily.
• Computer understands sequences of 1s and 0s (bits).
• Eight bits make a byte, the common unit of storage
• Each memory location has a name or number, and a size indicating the type of data it can store.
• Examples: Postcards Jim (only holds postcards); Packages Mary (holds large packages).
• Memory locations are identified by data type and name (e.g., float radius).

Variables and Constants

• Variables are memory locations where values can change during program execution.
• Constants are memory locations where values are fixed and do not change.
• Constants are usually defined in the header section.
• Variables are usually defined in the main section

Data Types

• Integer: Whole numbers (e.g., 1, 2, -3). Three types: short, int, long.
• Floating point: Numbers with decimal points (e.g., 3.14, -2.99). Two types: float, double.
• Character: Single letters, digits, and special characters (e.g., 'a', '8', '?').
• Boolean: Represents true or false values.

Identifiers

• Identifiers are used to name variables, constants, and other program components.
• Identifiers must start with a letter or underscore, followed by letters, digits, or underscores.
• C++ is case-sensitive (e.g., simple, Simple, SIMPLE are different identifiers).

Output Statements

• cout (standard output stream) displays information on the screen.
• Values are output using the << operator, such as cout << "The value of total is " << total;.
• endl inserts a new line after output

Input Statements

• cin (standard input stream) gathers input from the keyboard.
• Input values are stored in variables using the >> operator, such as cin >> grade;.
• Statements that ask for user input are called prompts.

Strings

• string is a data type that can hold sequences of characters (e.g., names).
• Enclose strings in double quotes (e.g., "Daniel").
• Use getline(cin, variable_name); to read in strings containing spaces.

Assignment Statements

• The = operator is for assigning values.
• The variable gets the value from the right side. Expressions on the right side can contain literals or variables, and = is not the same as equality in mathematics.

Formatted Output

• C++ offers ways to control output spacing, decimal precision, and formatting.
• setw() for spacing.
• setprecision() for decimal precision.

Arithmetic Operators

• The basic arithmetic symbols are +, -, *, /, %.
• Note the integer division, which truncates the fraction part.

Logical Operators

• Logical operators combine relational expressions (e.g., && for AND, || for OR , ! for NOT)
• Evaluating conditions using these logical operators

Conditional Statements ( if, If/Else, If/else if)

• Allows code to execute blocks of instructions only if specific conditions are met.
• if statement runs a block of code if the test condition is true.
• if/else statement runs one block of code if true and another if false.
• if/else if statement is for several conditions.

Switch Statements

• Allows executing different blocks based on the value of an integer variable.
• Cases and break; statements direct execution to the appropriate case.

Loops

• While Loops: Execute a block of code as long as a condition (expression) is true.
• Do-While Loops: Execute a block of code at least once, and then repeat as long as a condition is true.

For Loops

• for loops provide a structured way for repeated execution of code based on a counter.
• Initialize (first expression), the test condition (second expression), update a counter (third expression)

Nested Loops

• One loop within another loop is nested.
• Execution takes place in a predefined sequence.