How to state valid characters are alphanumeric and 'all keyboard symbols'?

1. How do you write alphanumeric characters?
2. What is alphanumeric with symbols?

How do you write alphanumeric characters?

Alphanumeric characters are the numbers 0-9 and letters A-Z (both uppercase and lowercase). An alphanumeric example are the characters a, H, 0, 5 and k. These characters are contrasted to non-alphanumeric ones, which are anything other than letters and numbers.

What is alphanumeric with symbols?

Alphanumeric Defined

Alphanumeric, also known as alphameric, simply refers to the type of Latin and Arabic characters representing the numbers 0 - 9, the letters A - Z (both uppercase and lowercase), and some common symbols such as @ # * and &.