Question 1

What is ASCII?

Accepted Answer

ASCII (American Standard Code for Information Interchange) is a 7-bit character encoding standard that maps 128 characters (codes 0–127) to numeric values. It defines two groups: control characters (0–31 and 127) — non-printing signals like newline (LF, 10), carriage return (CR, 13), tab (HT, 9), and null (NUL, 0); and printable characters (32–126) — letters, digits, punctuation, and space. ASCII is the foundation of virtually all modern text encoding.

Question 2

History of ASCII

Accepted Answer

ASCII was developed in the early 1960s and first published as a standard in 1963 by the American Standards Association (now ANSI). It became the universal encoding for early computer systems, telecommunications, and the internet. Today, UTF-8 — the dominant encoding on the web (used by over 98% of websites) — is a superset of ASCII: the first 128 code points are identical, ensuring full backward compatibility. Every valid ASCII document is automatically valid UTF-8.

Question 3

When do you need ASCII codes?

Accepted Answer

Debugging — identify invisible control characters (null bytes, carriage returns, escape sequences) causing issues in files or network data. Programming — convert between characters and their numeric values for low-level string operations, encryption algorithms, and protocol implementations. HTML entities — use ASCII codes to represent special characters in HTML (e.g., &#60; for <). Data validation — check if input contains only printable ASCII characters (codes 32–126) to prevent encoding issues.

Question 4

Frequently referenced ASCII codes

Accepted Answer

0 (NUL): Null — string terminator in C/C++. 9 (HT): Horizontal tab — 	 in most languages. 10 (LF): Line feed — newline on Unix/macOS (
). 13 (CR): Carriage return — Windows uses CR+LF (
) for newlines. 27 (ESC): Escape — starts ANSI terminal color/formatting sequences. 32 (SP): Space — first printable character. 48–57: Digits 0–9. 65–90: Uppercase A–Z. 97–122: Lowercase a–z. The difference between uppercase and lowercase is always 32 (e.g., A=65, a=97).

ASCII Table

What is ASCII?

History of ASCII

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