Latin Small Letter D
The fourth of the six hexadecimal letter-digits, lowercase 'd' represents the value 13 and sits at ASCII code point 100 (0x64) — a clean decimal landmark within the character table. It is the fourth letter of the Latin alphabet, a voiced alveolar plosive that accounts for roughly 4.3 % of characters in typical English corpora, and rests 32 positions above its uppercase counterpart 'D' at 68 (0x44), maintaining the standard single-bit case offset (bit 5) in ASCII.
Technical Details
Code Example
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// %d format specifier for integersint value = 42;printf("Value: %d\n", value); // Value: 42printf("Hex: %x\n", value); // Hex: 2a
Common Usage
Hexadecimal digit: As the fourth hex letter-digit, 'd' represents 13 and appears throughout MAC addresses (aa:bb:cc:dd…), SHA digests, and CSS shorthand colors (#ddd for a light grey). Because 0x64 equals 100 in decimal, it can serve as a quick sanity landmark when scanning hex tables.
Regex digit shorthand: The escape \d is one of the most widely used character-class shorthands in regular expressions, typically matching ASCII decimal digits [0–9] in engines such as PCRE, Python, JavaScript, and Java — though behavior may differ in Unicode mode. Its negation \D typically matches everything that is not a digit.
Format specifier for integers: In C-family printf-style formatting, %d formats a signed decimal integer — likely the first format token most programmers encounter. Similar syntax appears in Python 2 string formatting, Perl, Ruby, and Go's fmt package, though details vary by language.
Diacritical variants: Several orthographies modify 'd' — đ (stroke) is a distinct letter in Croatian, Vietnamese, and Serbian Latin; ď (caron) appears in Czech and Slovak; and ḍ (dot below) is used in IAST transliteration of Sanskrit and in some African language orthographies.
Hexadecimal digit: As the fourth hex letter-digit, 'd' represents 13 and appears throughout MAC addresses (aa:bb:cc:dd…), SHA digests, and CSS shorthand colors (#ddd for a light grey). Because 0x64 equals 100 in decimal, it can serve as a quick sanity landmark when scanning hex tables.
Regex digit shorthand: The escape \d is one of the most widely used character-class shorthands in regular expressions, typically matching ASCII decimal digits [0–9] in engines such as PCRE, Python, JavaScript, and Java — though behavior may differ in Unicode mode. Its negation \D typically matches everything that is not a digit.
Format specifier for integers: In C-family printf-style formatting, %d formats a signed decimal integer — likely the first format token most programmers encounter. Similar syntax appears in Python 2 string formatting, Perl, Ruby, and Go's fmt package, though details vary by language.
Diacritical variants: Several orthographies modify 'd' — đ (stroke) is a distinct letter in Croatian, Vietnamese, and Serbian Latin; ď (caron) appears in Czech and Slovak; and ḍ (dot below) is used in IAST transliteration of Sanskrit and in some African language orthographies.