Definition and initialization methods of basic data type constants study guide

To learn the definition and initialization method of basic data type constants, specific code examples are required

In programming, various basic data types are often used, such as integers , floating point type, character type, etc. When using these data types, you not only need to understand their definition and usage, but also how to define and initialize their constants. This article will introduce you to the definition and initialization method of basic data type constants, and give specific code examples.

1. Definition and initialization method of integer constants

Integer constants include four types: int, long, short and byte. They respectively represent different integer ranges, as follows:

• int: represents an integer, occupies 4 bytes, and ranges from -2147483648 to 2147483647.
• long: Represents a long integer, occupying 8 bytes, ranging from -9223372036854775808 to 9223372036854775807.
• short: Represents a short integer, occupying 2 bytes, ranging from -32768 to 32767.
• byte: Represents byte, occupies 1 byte, range is -128 to 127.

The way to define an integer constant is very simple, just assign a certain value directly when the variable is declared. For example:

int num1 = 10; // Define a constant num1 of type int, with an initial value of 10
long num2 = 1000000000; // Define a constant num2 of type long, with an initial value of 1000000000
short num3 = 100; // Define a short type constant num3 with an initial value of 100
byte num4 = -50; // Define a byte type constant num4 with an initial value of -50

2. Definition and initialization method of floating-point constants

Floating-point constants include float and double types. They are used to represent values ​​with decimal points, as follows:

• float: represents a single-precision floating point number, occupying 4 bytes and having 6 significant digits.
• double: represents a double-precision floating-point number, occupying 8 bytes and having 15 effective digits.

Similarly, the method of defining floating-point constants is also very simple, just assign a certain value directly when the variable is declared. For example:

float num5 = 3.14f; // Define a float type constant num5 with an initial value of 3.14
double num6 = 3.1415926535; // Define a double type constant num6 with an initial value of 3.1415926535

It should be noted that when assigning a value to a float type constant, you need to add the suffix "f" after the value to clearly indicate it as a float type.

3. Definition and initialization method of character constants

Character constants are used to represent a single character and are enclosed in single quotes. For example:

char ch1 = 'A'; //Define a character constant ch1 with an initial value of 'A'

It should be noted that a character constant can only represent a single character. Cannot represent a string. If you need to represent a string, you need to use the string type (String).

4. Definition and initialization method of Boolean constants

Boolean constants are used to represent two values ​​​​of true (true) or false (false), occupying only one byte Space. For example:

boolean flag1 = true; // Define a Boolean constant flag1 with an initial value of true
boolean flag2 = false; // Define a Boolean constant flag2 with an initial value of false

Boolean constants can only take the value true or false, and cannot be directly assigned to other non-Boolean values.

Summary:

In this article, we learned the definition and initialization method of basic data type constants, and gave specific code examples. During the programming process, we often need to use integer, floating-point, character and Boolean constants. By defining and initializing constants in a suitable way, we can write programs more conveniently. I hope this article will be helpful for everyone to learn basic data type constants.

The above is the detailed content of Definition and initialization methods of basic data type constants study guide. For more information, please follow other related articles on the PHP Chinese website!