What are Multicharacter Literals in C and C , and How Are They Used?

Multicharacter Literals in C and C : Purpose and Usage

The C and C languages feature multicharacter literals, which are sequences of more than one character enclosed in single quotes. These literals differ from single-character literals, such as 'c', in that they evaluate to integer values, not character values.

According to the C99 standard, the value of a multicharacter integer constant is implementation-defined. However, in practice, these literals are often used to represent non-printable characters or escape sequences that cannot be conveniently represented in a single byte.

One common use of multicharacter literals is for debugging purposes. By assigning mnemonic names to integer values, developers can make memory dumps more readable. For example, the following code defines an enumerated type with symbolic names for different states:

enum state { waiting, running, stopped };

After the statement s = stopped; is executed, a memory dump might look like:

00 00 00 02 . . . .

In contrast, if multicharacter literals are used:

enum state { waiting = 'wait', running = 'run.', stopped = 'stop' };

the same memory dump would appear as:

73 74 6F 70 s t o p

making it easier to identify the state.

Multicharacter literals are also useful for representing compressed strings. By storing the string as an integer value instead of a sequence of characters, space can be saved. However, it is important to note that multicharacter literals are not as portable as single-character literals, as the underlying representation may vary across different platforms.

In C , multicharacter literals are primarily used for compatibility with C code. However, they are generally not considered to be a bad feature, as they can provide certain benefits in specific scenarios.

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