The difference between single and double quotes in C language

In C language, single quotes define character constants, and double quotes define string constants. Single quotes can also define preprocessor macros, which have different scope and precedence than double quotes. Although both can define strings, it is recommended to use double quotes in preference as it supports escape characters.

The difference between single and double quotation marks in C language

Clear answer:

In the C language, single quotes (') and double quotes (") are used to define character constants and string constants. The main differences are:

1. Character constants

• Single quotation marks are used to define a single character, such as: 'a', '5'.
• Double quotation marks cannot be used to define a single character. ##2. String constants

Both single quotes and double quotes can be used to define strings, that is, constants composed of a series of characters.

Double quotes define. The string can also contain escape characters, such as:

• <code class="c">"Hello, world!\n" // 换行符</code>

• 3. The preprocessor macro

single quotes can also be used to define Preprocessor macros, such as:

<code class="c">#define PI 3.14159265</code>

• 4. Scope

##The scope of symbols defined by single quotes and double quotes is different. Symbols defined are only visible during compilation, while symbols defined with double quotes are visible during runtime

5. Priority

##Single quotes. Different from the priority of double quotes in the preprocessing stage, single quotes have higher priority than double quotes, so when nesting macros, use single quotes in the outer layer and double quotes in the inner layer.

Example:

<code class="c">#define FOO(x) "Hello, " #x "!"
FOO(World) // "Hello, World!"</code>

Note:

Although single and double quotation marks can be used to define strings, in actual use, It is generally recommended to use double quotes because it can contain escape characters, increasing the flexibility of the string .

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