A statement is a type of instruction that causes the program to perform some action. Statements are often terminated by a semicolon.
A function is a collection of statements that execute sequentially. Every C++ program must include a special function named main. When you run your program, execution starts at the top of the main function.
In programming, the name of a function (or object, type, template, etc.) is called its identifier.
The rules that govern how elements of the C++ language are constructed is called syntax. A syntax error occurs when you violate the grammatical rules of the language.
Comments allow the programmer to leave notes in the code. C++ supports two types of comments:
- Line comments start with
// - Block comments use
/* */
Data is any information that can be processed by a computer. A single piece of data is called a value.
A variable is created using a definition statement. When defined, variables are instantiated (assigned memory addresses).
A data type tells the compiler how to interpret data. An integer is a number without fractional components.
Initialization specifies an initial value for an object. C++ supports 6 initialization types:
| Initialization Type | Example | Note |
|---|---|---|
| Default-initialization | int x; |
Indeterminate value |
| Copy-initialization | int x = 5; |
|
| Direct-initialization | int x(5); |
|
| Direct-list-initialization | int x{5}; |
No narrowing conversions |
| Copy-list-initialization | int x = {5}; |
No narrowing conversions |
| Value-initialization | int x{}; |
Zero-initialization |
std::cout and operator<< handle console output. std::endl flushes output while '\n' does not.
An uninitialized variable causes undefined behavior if accessed. C++ keywords cannot be used as identifiers.
A literal constant is a fixed value in source code (e.g., 5, "Hello").
Operations involve operands and operators:
- Unary: 1 operand
- Binary: 2 operands
- Ternary: 3 operands
- Nullary: 0 operands
An expression produces a single value through evaluation. An expression statement adds a semicolon to an expression.