ASCII 228
Lowercase a with umlautGreek capital sigma
ASCII 228 is ä on Windows and Σ in old DOS.
ä (Small A with Umlaut) is byte 228 in Windows-1252, Unicode U+00E4. German writes März and Käse with it, Swedish and Finnish treat it as a separate letter, and Slovak has it too. Email shows it in an odd form. Mail headers are ASCII-only, so a subject line like März travels as an encoded word, either =?UTF-8?Q?M=C3=A4rz?= with the UTF-8 bytes C3 A4 written as =C3=A4, or a Base64 variant marked ?B?. If a log, script or badly configured client prints that string raw, decode it with a MIME library such as Python's email.header.decode_header rather than by hand. Old DOS had ä at 132. The UTF-8 bytes C3 A4 misread as ä. The HTML entity is ä.
Σ (Capital Sigma) is byte 228 in code page 437, the original IBM PC character set, and maps to Unicode U+03A3. Maths uses it for sums, though Unicode also has a dedicated summation sign ∑ (U+2211). Lowercasing it is the tricky part. Greek has two small sigmas, σ inside a word and ς at the end, so the correct lowercase depends on position. Python's str.lower() handles that and turns ΟΔΟΣ into οδος, but code that lowercases one character at a time always produces σ. Code page 437 has σ at 229 and no ς at all. Code page 850 put õ on this byte. In UTF-8, Σ is CE A3, and the HTML entity is Σ.
Technical Details
Technical Details
Code Example
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#include <stdio.h>int main(void) {/* On Windows (code page 1252) byte 228 is ä.Modern terminals expect UTF-8, so print the code point, not the byte. */printf("\u00E4\n"); /* UTF-8: C3 A4 */unsigned char b = 228; /* the raw Windows-1252 byte */printf("%d 0x%02X\n", b, b); /* 228 0xE4 */return 0;}
Code Example
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#include <stdio.h>int main(void) {/* Byte 228 is Σ only on a console using code page 437(chcp 437 on Windows, or DOSBox). On a UTF-8 terminal thelone byte 0xE4 is invalid and prints as garbage, often �. */putchar(228);/* char is signed on x86, so a plain char holding 0xE4 is -28.Use unsigned char when you compare or index by byte value. */char c = (char)228;unsigned char u = 228;printf("\n%d %d\n", c, u); /* -28 228 *//* Portable: print the Unicode character as UTF-8 instead. */printf("\u03A3\n"); /* CE A3 */return 0;}
How to Type It
- Windows
- Hold Alt and type 0228 on the numeric keypad, with Num Lock on. The leading zero picks the Windows code page. Alt+132, without the zero, types it too. No numeric keypad? In Word, type 00E4 and press Alt+X.
- Mac
- Press Option+U, then a.
- Linux
- In GNOME, or any desktop running IBus, press Ctrl+Shift+U, type e4, then Space. With a Compose key set up, press Compose, quote, a.
- Phone
- Long-press a and pick ä.
How to Type It
- Windows
- Hold Alt and type 228 on the numeric keypad, with no leading zero. US PCs insert Σ, but PCs set to code page 850, common in Western Europe, insert õ. No numeric keypad? In Word, type 03A3 and press Alt+X.
- Mac
- Press Control+Command+Space to open the Character Viewer, then search for "greek capital letter sigma". Option+W gives ∑ (n-ary summation), which looks similar but is a different character.
- Linux
- In GNOME, or any desktop running IBus, press Ctrl+Shift+U, type 3a3, then Space.
- Phone
- Add the Greek keyboard in your phone's keyboard settings and type Σ there, or tap the character at the top of this page to copy it.
Frequently Asked Questions
Git quotes file names that contain bytes above 127 and writes each of those bytes in octal, so the UTF-8 bytes of ä, C3 A4, come out as \303\244. Turn it off once with `git config --global core.quotePath false` and git status prints the real name. The file itself was never damaged.
It depends on the language. Swedish and Finnish put ä near the end of the alphabet, after z and å, while German files it with a, so the same list sorts differently in Stockholm and Berlin. Sorting by code point matches neither. Pass the locale: `names.sort(new Intl.Collator('sv').compare)` for Swedish, and 'de' for German.
Reimport it and tell the import that the file is UTF-8. In LibreOffice Calc, the Text Import dialog that opens with a CSV has a Character set list, and choosing Unicode (UTF-8) there fixes the preview before anything is loaded. If the file comes from your own export, writing it with a BOM lets it open correctly without touching that setting.
The batch file was saved in Windows-1252, and cmd reads it through the console's DOS code page. On German Windows that's 850, where the ä byte is õ, and on US systems it's 437, where the same byte is Σ. Put `chcp 1252 >nul` as the first line, and cmd reads the rest of the file the way it was saved.
Frequently Asked Questions
The batch file was saved in Windows-1252, and cmd reads it through the console's DOS code page. On German Windows that's 850, where the ä byte is õ, and on US systems it's 437, where the same byte is Σ. Put `chcp 1252 >nul` as the first line, and cmd reads the rest of the file the way it was saved.