Invalid Data Type in C: char*

Explanation:

In C programming, there are several data types that are used to represent different kinds of values such as integers, floating-point numbers, characters, etc. However, one of the options mentioned in the question, char*, is not a valid data type in C.

Here's a detailed explanation:

1. Valid Data Types in C:
- float: This data type is used to represent single-precision floating-point numbers.
- bool: This data type is used to represent boolean values, which can be either true or false.
- long long: This data type is used to represent large integers that require more storage than the standard int data type.

2. Invalid Data Type: char*
- char*: This is not a valid data type in C. It seems to be a combination of two valid data types, char and *. In C, char is used to represent individual characters, while * is used to declare a pointer variable. However, combining them together as char* does not create a valid data type.

3. Valid Alternatives:
- char: This data type is used to represent individual characters.
- char[]: This data type is used to represent strings or arrays of characters.
- char*: This data type is used to declare a pointer to a character or a string.

4. Usage of char*:
- While char* is not a valid data type in C, it is commonly used to represent strings by declaring a pointer to a character or a string. For example, char* str = "Hello"; declares a pointer variable str that points to a string "Hello".

In conclusion, the invalid data type among the options provided is char*. It is important to understand the different data types in C and their appropriate usage to write correct and efficient programs.