How to search and reverse look up characters/control characters in the ASCII code table

When this guide is useful

This is for users who want to check the ASCII code table, ASCII decimal/hexadecimal conversion, reverse character code lookup, control character list, and the meanings of NUL, TAB, LF, and CR.

• Check if 0x0A in the log is LF
• Additional information: A 10 16 2
• Additional information for this feature.

Information that can be confirmed in the ASCII code table

• Additional information: ASCII 0～127
• Decimal, hexadecimal, octal, binary, Unicode notation
• Abbreviations and explanations of NUL, TAB, LF, CR, ESC, DEL, etc.
• Notation used in C, Java, JavaScript, Python, and HTML

Steps to reverse lookup of ASCII characters

1. Input
2. Input
3. Check the English name, Japanese description, classification, and value of each base number.
4. Copy

Notes on extended ASCII and character codes

128-255 is not a single ASCII standard, but has different assignments for Windows-1252, ISO-8859-1, and various code pages. Also not to be confused with UTF-8 1-byte values.

Control characters such as TAB and newline are not visible on the screen. When copying actual data, make sure that the destination does not cause unexpected behavior.

Specific example: Check the difference between 0x0A and 0x0D

0x0A is LF, 0x0D is CR, and the combination of line feed codes differs depending on the OS and protocol.

Don't judge based on numbers alone; check whether CRLF or LF is required in the specifications.

1. Enter 0x0A to confirm LF.
2. Enter 0x0D to confirm CR.
3. Compare escape notation \n and \r.
4. Check the line breaks expected by the target file and communication specifications.

When converting text files to line breaks, check not only the content but also the line break settings in Git and the editor.

Frequently asked questions

Are ASCII and Unicode the same?

ASCII 0-127 has the same mapping as Unicode's U+0000-U+007F, but Unicode contains far more characters.

Aren't 128-255 also ASCII?

Although it is commonly referred to as Extended ASCII, it is not included in Standard ASCII because each code page has different characters.