C++ Lessons : 8.1. Numeric Data Type

[quix]

Numeric Types

Use int when you need to store a whole number without decimals, like 35 or 1000, and float or double when you need a floating point number (with decimals), like 9.99 or 3.14515.

int

int myNum = 1000;
cout << myNum;

float

float myNum = 5.75;
cout << myNum;

double

double myNum = 19.99;
cout << myNum;

float vs. double

The precision of a floating point value indicates how many digits the value can have after the decimal point. The precision of float is only six or seven decimal digits, while double variables have a precision of about 15 digits. Therefore it is safer to use double for most calculations.

Scientific Numbers

A floating point number can also be a scientific number with an "e" to indicate the power of 10:

Example

float f1 = 35e3;
double d1 = 12E4;
cout << f1;
cout << d1;