Input and Output

What is an identifier? What are the ways to give value to variable? Explain with example. Explain how scanf() and printf() are used. Write syntax and use of gets(), getchar(), getche(), putchar().

Differentiate between unformatted and formatted input/output in C.

Write syntax and example of the following: (i) getch() (ii) gets() (iii) printf() (iv) scanf().