Which of the following functions is not declared in <stdio.h>?

Correct option is D

In the C programming language, the header file <stdio.h> contains declarations related to standard input and output functions such as printf(), scanf(), fprintf(), and file handling functions like fopen().

The function sqrt() is used to calculate the square root of a number and is declared in the <math.h> header file, not in <stdio.h>.

Therefore, sqrt() is the correct answer.

Important Key Points:

1. <stdio.h> stands for Standard Input Output Header in C.
2. Functions like printf() and scanf() are used for console input and output operations.
3. fopen() and fprintf() are file handling functions available in <stdio.h>.
4. sqrt() belongs to the <math.h> library because it performs mathematical operations.

Knowledge Booster:

1. (a) printf(): Incorrect because printf() is a standard output function declared in <stdio.h>.
2. (b) scanf(): Incorrect because scanf() is a standard input function declared in <stdio.h>.
3. (c) fopen(): Incorrect because fopen() is a file handling function available in <stdio.h>.
4. (e) fprintf(): Incorrect because fprintf() is a formatted file output function declared in <stdio.h>.