| Decimal | Hex | Octal | Binary | Char | HTML Entity | Description |
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This ASCII table lookup tool is a practical reference for developers and learners. Here is a detailed usage guide:
Basic Lookup: When you open the page, the full table of all 128 ASCII characters is displayed by default. The table shows decimal value, hexadecimal value, octal value, binary value, character display, HTML entity encoding, and character description from left to right. You can browse directly to find the character information you need.
Category Filtering: Click the filter tags above the table (All, Control, Printable, Digits, Uppercase, Lowercase, Punctuation) to quickly filter characters by category. For example, selecting the "Digits" tag will show only the characters 0-9 (ASCII values 48-57).
Search Function: Enter keywords in the search box. You can search by decimal value (e.g., "65"), hexadecimal value (e.g., "41"), the character itself (e.g., "A"), or description text (e.g., "newline", "LF"). Search results update in real time for quick targeting.
One-Click Copy: Click any numeric value in the table (such as decimal or hexadecimal) to copy it to the clipboard. A "Copied" hint appears at the top of the page for easy use in your code. Clicking a character row expands the detail panel with complete encoding information for that character.
The ASCII table has broad applications in programming and systems development. Here are several typical examples:
Serial Communication Debugging: In embedded development and IoT projects, serial communication is the primary method of data exchange between devices. Developers often need to send specific control characters (such as SOH, STX, ETX) to mark the start and end of data frames. This tool helps developers quickly look up the decimal or hexadecimal values of these control characters to ensure correct implementation of communication protocols.
Text File Format Conversion: Different operating systems use different line endings: Windows uses CRLF (ASCII 13+10), Unix/Linux uses LF (ASCII 10), and legacy Mac uses CR (ASCII 13). During cross-platform development or file processing, understanding these differences is crucial. This tool visually displays the values and meanings of these control characters, helping troubleshoot line break-related issues.
HTML Entity Encoding: In web development, certain special characters (such as <, >, &) must be escaped as HTML entities to display correctly on web pages. This tool provides the HTML entity encoding for each ASCII character (such as <, >, &), allowing developers to quickly query and use them.
ASCII Encoding History: ASCII (American Standard Code for Information Interchange) was first published in 1963 and updated in 1967. It is one of the most important encoding standards in computer history. It defines an encoding scheme for 128 characters covering English letters, digits, punctuation, and control characters. ASCII was designed around the keyboard layout of teletype machines, so character order corresponds to actual keyboards. Before Unicode, ASCII was the universal standard for English-language computer communication.
Extended ASCII (EASCII): Standard ASCII uses 7-bit encoding (128 characters), but after 8-bit bytes became the standard, the extra 128 positions (128-255) were used to define Extended ASCII character sets. Different countries and regions adopted different Extended ASCII encodings, such as ISO-8859-1 (Western European), ISO-8859-5 (Cyrillic), and Windows-1252. This was also the root cause of early "garbled text" issues.
ASCII Art: ASCII art is a form of visual art created using ASCII characters (mainly printable ones). From simple emoticons like :-) to complex pixel art, ASCII art demonstrates remarkable creativity in text-only environments. Early computer games, forum signatures, and source code comments often featured ASCII art.
The standard ASCII table has 128 characters, numbered from 0 to 127. Characters 0-31 and 127 are control characters (33 total), and characters 32-126 are printable characters (95 total). Printable characters include digits (48-57), uppercase letters (65-90), lowercase letters (97-122), and punctuation symbols.
Control characters (0-31, 127) are invisible special characters used to control device behavior, such as line feed (LF, 10), carriage return (CR, 13), and tab (TAB, 9). Printable characters (32-126) are visible characters that can be displayed on screen, including letters, digits, punctuation, and spaces.
ASCII is a subset of Unicode. The first 128 characters of Unicode (U+0000 to U+007F) correspond exactly to ASCII, so any ASCII-compatible text has identical byte representation in UTF-8 encoding. ASCII serves as the foundation of Unicode compatibility.
ASCII was originally designed as a 7-bit encoding scheme (2^7 = 128 characters) because early telecommunication equipment and computers used 7-bit data channels. Later, Extended ASCII (EASCII, 2^8 = 256 characters) was developed using 8 bits, but standard ASCII only defines the first 128 characters.
Most programming languages provide built-in methods to get a character's ASCII value. In JavaScript, use charCodeAt(). In Python, use ord(). In Java, cast the char to int. In C/C++, a char is essentially its ASCII integer value.
NUL (null character, ASCII value 0) is used as a string terminator in C, marks the end of fields or records in databases and file processing, and is used for memory initialization and data padding in modern programming.
CRLF (carriage return + line feed, ASCII 13+10) is the line ending used by Windows. LF (line feed, ASCII 10) is the line ending used by Unix/Linux and macOS. This difference often causes line break inconsistencies when transferring text files between systems.