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C++ Numeric Data Types

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 myNum = 1000;
cout << myNum;
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float myNum = 5.75;
cout << myNum;
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double myNum = 19.99;
cout << myNum;
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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:


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