Summary - Variables
- C++ course
- Beginner
- Lesson 12/116
- 5 min
Declare typed variables to write a small profile program.
Summary - Variables
In this section you learned the basics of variables:
- declaring variables with int, double, char, bool, float
- auto for compiler type deduction
- const for immutable variables
- constexpr for compile-time constants
- static_cast for safe type conversion
Now you will reinforce these concepts with two mini tasks.
Practice Print three types on one line
Inside main, declare an int (value 5), a double (value 1.5) and a char (value 'X'). Chain all three in a single std::cout line and end with std::endl.
Starter code
#include <iostream>
int main() {
// Declare an int, a double and a char
// Print all three on one line with std::cout
return 0;
}Sample solution
#include <iostream>
int main() {
// Declare an int, a double and a char
int count = 5;
double rate = 1.5;
char label = 'X';
// Print all three on one line with std::cout
std::cout << count << rate << label << std::endl;
return 0;
}Expected output
51.5X
Practice Constant and conversion together
Inside main, declare const double pi = 3.14159;. Use static_cast<int> to convert pi to int and assign it to a variable named rounded. Then print rounded with std::cout using std::endl.
Starter code
#include <iostream>
int main() {
// Define const double pi
// Convert pi to int with static_cast and print
return 0;
}Sample solution
#include <iostream>
int main() {
// Define const double pi
const double pi = 3.14159;
// Convert pi to int with static_cast and print
int rounded = static_cast<int>(pi);
std::cout << rounded << std::endl;
return 0;
}Expected output
3
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Immutable variable
Question
____ int maxLevel = 50;
Answer
const int maxLevel = 50;Explanation: const int maxLevel is immutable.
2 Match the section concepts
| Term | Meaning |
|---|---|
auto |
Type deduction |
const |
Immutable |
constexpr |
Compile time |
static_cast |
Type conversion |