What is the difference between a character constant and a string constant in C language?

In the C language, character constants consist of single characters enclosed in single quotes, for example, ‘a’. On the other hand, string constants consist of multiple characters enclosed in double quotes, for example, “hello”.

The differences are as follows:

1. Format: Character constants are enclosed in single quotes, while string constants are enclosed in double quotes.
2. Type: Character constants are of type char, while string constants are of type char array.
3. Storage method: Character constants occupy 1 byte in memory, storing the corresponding integer value of the ASCII code; string constants occupy multiple bytes in memory, stored in the form of strings.
4. End of line: Character constants do not require an end of line, while string constants need to have ‘\0’ as the end of line.
5. Assignment: Character constants can be directly assigned to character variables, string constants need to use the strcpy() function or be directly assigned to character arrays.
6. Usage: Character constants can be used in character-type operations, while string constants can be operated on using string-related library functions such as strlen() and strcat().
7. Variability: Character constants are immutable, and so are string constants.

In summary, character constants are constants made up of individual characters, while string constants are constants made up of multiple characters. They differ in representation, type, storage, termination, assignment, manipulation, and mutability.