C++ Programming Basics

C++ Programming Basics

• A computer program is a sequence of statements designed to achieve a specific task.
• Programming involves planning and creating a program.
• The first C++ program example includes <iostream> and using namespace std;.
• The cout statement displays output to the screen.
• The << symbol is the insertion operator.
• Basic C++ components include functions, special symbols, identifiers, data types, arithmetic operators, string data types, assignment statements, variable declarations, input data, increment/decrement operators, output statements, preprocessor directives, debugging, syntax errors, comments, and compound statements.

Steps to Process a C++ Program

• A C++ program is a high-level language, unlike machine language directly understood by computers.
• Steps for executing a C++ program:
  • Using a text editor or IDE, create the C++ source code (.cpp file).
  • The preprocessor processes statements starting with '#'.
  • The compiler (e.g., g++) checks the source code for syntax errors. If no errors are found, the compiler translates it to machine-language (object code, .o or .obj file).
  • A linker combines the object file with library files to create an executable file (.exe file).
  • The loader loads the executable file into memory for execution.
  • The program then runs.

Comments in C++

• Comments are notes within a program, intended for human readers, not the compiler.
• Line comments begin with //.
• Block comments begin with /* and end with */.

Preprocessor Commands

• Commands starting with # are preprocessor directives.
• #include <iostream> inserts the iostream library, enabling input/output operations using cout and cin.
• Header files, such as iostream, need to be included at the beginning of the source code.

Namespace

• using namespace std; allows access to standard library elements (e.g., cout, endl) without the std:: prefix.

Main Function

• The main() function is the entry point of a C++ program.

Variable Declaration

• Every variable needs a type declaration.
• The dataType variableName; format declares a variable.
• Example: double length; declares a variable named length to store a double-precision number.

Assignment Statements

• An assignment statement assigns a value to a variable.
• Example: length = 6.0; assigns the value 6.0 to the variable length.

Output with cout

• cout sends data to the screen.
• endl inserts a newline character.
• To display "Hello", use cout << "Hello";.

Arithmetic and String Expressions

• Expressions can be arithmetic (e.g., 7 + 8) or string (e.g., "Length =").
• Arithmetic expressions are evaluated according to standard arithmetic rules.
• The output statement can combine strings and variables.
• For example, cout << "Length = " << length << endl; shows "Length = " followed by the value of the variable length.