1. What is this?
A variable is a named slot in memory. A type fixes what fits: int (whole numbers), double (decimals), std::string (text, needs #include <string>), bool (true/false). int age = 28 reserves an integer slot called age with value 28.
2. Why do we use it?
C++ gives you control over memory and speed. Types are the contract that makes that control safe.
3. Syntax breakdown
int age = 28;
Integer variable age holding 28.
std::string name = "Ava";
Text variable. Needs #include <string>.
std::cout << name << " is " << age << std::endl;
<< chains values into one line of output.
5. Common mistakes
- Using std::string without #include <string>.
- Assigning "28" (text) to an int.
- Single vs double quotes: "Ava" is a string, 'A' is a single char.
Practice task
Add std::string city = "Berlin"; and print "I live in Berlin."
Hint
Declare city, then cout << "I live in " << city << "." << endl;
Try it below — tests run automatically when you press Run.
Output
Press Run to see output.
Mini quiz
3 questions. Answer, then check.
1. Which type holds whole numbers?
2. Which header does std::string need?
3. What does << do with cout?