How many digits does java long have?

java long is 64 bits. The long data type is a 64-bit signed Java primitive data type. It is used when the calculation result of an integer may exceed the range of the int data type. Its value range is -9223372036854775808 to 9223372036854775807. All integers within the range of long are called integer literals of long type. Integer constants of long type always end with L or lowercase l, for example "long num1 = 0L;".

The operating environment of this tutorial: windows7 system, java8 version, DELL G3 computer.

Java long data type

The long data type is a 64-bit signed Java primitive data type.

Use when the calculation result of an integer may exceed the range of the int data type.

The range is -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.

All integers within the range of long are called integer literals of type long. Integer constants of type long always end in L or lowercase l.

The following is an example of using an integer literal of type long:

long  num1 = 0L; 
long  num2 = 4L; 
long  mum3  = -3; 
long  num4 = 8; 
long  num5 = -1L;

Long integer literal

The integer literal of type long can be used Represented in octal, hexadecimal and binary formats. For example,

long  num1;
num1 = 25L;       // Decimal  format 
num1 = 031L;      // Octal format
num1 = 0X19L;     // Hexadecimal  format 
num1 = 0b11001L;  // Binary   format

When a long literal is assigned to a variable of type long, the Java compiler checks the value to be assigned and ensures that it is within the scope of the long data type; otherwise a compile-time error is generated.

Note: Assignment from int to long is valid because all values ​​that can be stored in an int variable can be stored in a long variable. However, the opposite is not true. You cannot simply assign the value stored in a long variable to an int variable. There is a possibility of value overflow.

To assign the value of a long variable to an int variable, use "cast" in Java as follows:

num1 = (int)num2;

Java has a class Long which defines two A constant to represent the maximum and minimum values ​​of the long data types Long.MAX_VALUE and Long.MIN_VALUE.

long  max = Long.MAX_VALUE;
long  min = Long.MIN_VALUE;

Extended knowledge: The following code can see how big the 64-bit value is

Long.MAX_VALUE // Prints 9,223,372,036,854,775,807
Long.MIN_VALUE // Prints -9,223,372,036,854,775,808

Perhaps, long can be used to calculate the distance traveled by light in a certain period of time. Light travels approximately 300,000 kilometers in one second. If you write a program to track the distance traveled by light, the int type will be out of range class after 7 seconds, while the long type will be able to calculate about 975 years. Don't believe it? You can take a look at the calculations in this gist (https://gist.github.com/jrg94/820d3f0f482dd19f0170964346381df0).

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