Course Content
C++ Introduction
C++ Introduction
Numerical Data Types
Whole numbers
Integer data types are the most commonly used for whole numbers. The int
data type can hold values within the range of -2,147,483,648
to 2,147,483,647
.
main
#include <iostream> int main() { int goodNumber = 12; int tooLarge = 2147483648; std::cout << "Printing tooLarge: " << tooLarge << std::endl; std::cout << "Printing goodNumber: " << goodNumber << std::endl; }
That happens because when you declare an int
variable, it allocates precisely 4 bytes of your PC's memory. And numbers above 2147483647
(or below -2147483648
) do not fit inside those 4 bytes. Luckily, other data types available can allocate you more(or less) space for your needs. Here is the table:
Data Type | ||
short | 2 bytes | |
int | 4 bytes | |
long | 8 bytes |
So you can use long
to store large numbers (e.g., World's population). You can also use short
if you are sure your number will not exceed the -32,768
to 32,767
range (e.g., storing a user's age). Using short
will take up less space.
main
#include <iostream> int main() { short age = 22; int likes = 143200; long population = 7900000000; std::cout << "Age: " << age << std::endl; std::cout << "Likes: " << likes << std::endl; std::cout << "World's population: " << population << std::endl; }
Note
Be careful with the data type you choose. If the range of a type is exceeded, the C++ compiler will not tell you this, and you will get an unexpected value without knowing something is wrong.
Floating point numbers
The data types above are designed to store whole numbers. If we tried to assign 1.6
to one of those, here is what we would get:
main
#include <iostream> int main() { int num = 1.6; std::cout << num << std::endl; }
The int
type ignores the decimal part of a number. The same story with short
or long
. To store the floating point(decimal) numbers, we should use either float
or double
data type.
Data Type | ||
float | ||
double |
Here is an example of using double
to store 1.6
.
main
#include <iostream> int main() { double num = 1.6; std::cout << num << std::endl; }
Note
Since the
float
type only has a precision of seven digits, the number123.456789
is already out of its range. It can lead to inaccurate results(as shown in the example below). So it is better to usedouble
by default unless you are surefloat
's precision is enough.
main
#include <iostream> int main() { float floatNum = 123.45678; double doubleNum = 123.45678; std::cout << "using float:" << floatNum - 123 << std::endl; std::cout << "using double:" << doubleNum - 123 << std::endl; }
Obviously, you can use float
or double
to store whole numbers since those are decimal numbers with a decimal part equal to 0. However, as a good practice, if a variable stores values that can only be whole numbers (e.g., population or likes), short
/int
/long
should be used.
main
#include <iostream> int main() { float price = 100; std::cout << "Price is: " << price << std::endl;; }
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