What are the different representations that can be used to represent string constants?

String constants refer to string values ​​that are used directly in the program. They are immutable. String constants can be represented in many different ways in different programming languages.

1. Use double quotes to express
The most common way to express string constants is to use double quotes to enclose the string, for example: "Hello, World!". This representation method is suitable for most programming languages, such as Java, C, C, C#, Python, etc. In this representation, double quotes must appear in pairs, and the string can contain any character except newlines.

Sample code (Java):

String s1 = "Hello, World!";
System.out.println(s1);

2. Use single quotes to indicate
In some programming languages, such as C, character constants and string constants are different. Character constants are expressed using single quotes, while string constants are expressed using double quotes. For example, 'A' is a character constant and "Hello" is a string constant.

Sample code (C):

char c = 'A';
printf("%c
", c);

char* s = "Hello";
printf("%s
", s);

3. Use three double quotes to express
In Python and other programming languages ​​​​supported by multi-line strings, you can use three double quotes (or three single quotes) to represent a multiline string constant. This representation makes it convenient to include multiple lines of text without using escape characters.

Sample code (Python):

s = """
This is a 
multi-line 
string.
"""
print(s)

4. Use escape characters to represent
In some cases, special characters need to be represented in string constants, such as newline characters, system characters, etc. Table symbols, double quotation marks, etc. At this time, escape characters can be used to represent special characters. Common escape characters include:

• : represents a newline character
• : represents a tab character
• \": represents a double quote
• \ : Indicates backslash

Sample code (C):

string s = "This is a line
This is another line";
cout << s << endl;

string s2 = "He said, "Hello!"";
cout << s2 << endl;

In summary, different programming languages ​​can have many different ways to represent string constants. Use double String constants can be represented by quotes, single quotes, triple double quotes, or escape characters, depending on the programming language and the needs of your code. Regardless of the representation method used, string constants are immutable. That is, it cannot be modified.

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