Référence de caractère numérique

What Are Numeric Character References?

Numeric character references (NCRs) are HTML escape sequences that represent any Unicode character by its code point number. They take two forms:

• Decimal: &#N; where N is a base-10 integer — e.g., © for ©
• Hexadecimal: &#xH; where H is a base-16 integer — e.g., © for ©

Both forms refer to the Unicode scalar value of the character. Since Unicode covers over 1.1 million code points, NCRs can represent virtually any character ever assigned — from basic Latin letters to rare CJK ideographs and emoji — using only ASCII characters in the source.

Decimal vs. Hexadecimal

Decimal NCRs (&#N;) are straightforward for readers who know the decimal code points of common characters (65 = 'A', 169 = '©'). Hexadecimal NCRs (&#xH;) align with how Unicode code points are conventionally written — U+00A9 maps directly to ©. When working with Unicode documentation or character tables that list code points in hex, the hex form is easier to use without mental conversion.

<!-- These are identical -->
&#65;     = &#x41;   = A
&#169;    = &#xA9;   = ©
&#8364;   = &#x20AC; = €
&#128512; = &#x1F600; = 😀

Valid Range

Valid code points for NCRs are: 1–55295 (U+0001–U+D7FF) and 57344–1114111 (U+E000–U+10FFFF). The surrogate range U+D800–U+DFFF is invalid and must not be encoded. U+0000 (NULL) is also excluded. Browsers may render other disallowed code points (such as U+0001–U+001F control characters) as the replacement character U+FFFD.

Supplementary Characters

NCRs fully support Unicode supplementary characters (code points above U+FFFF). In UTF-16 these require surrogate pairs, but in HTML you write a single NCR:

<!-- U+1F4A9 PILE OF POO — supplementary character -->
&#128169;      <!-- decimal -->
&#x1F4A9;      <!-- hex -->

This is one advantage of NCRs over raw UTF-16 encoding in old environments.

Practical Use

<!-- Escaping in content -->
<p>The formula is a &#60; b &lt; c</p>
<!-- &#60; and &lt; both render as < -->

<!-- Characters outside keyboard reach -->
<p>The currency symbol is &#x20B9; (Indian Rupee)</p>

<!-- In HTML attributes -->
<input placeholder="Enter &#x2764; here">

<!-- Emoji -->
<title>Unicode Guide &#x1F4DA;</title>

# Python: convert character to NCR
char = "©"
f"&#{ord(char)};"    # "©"
f"&#x{ord(char):X};" # "©"

# Python: decode NCR
import html
html.unescape("©")   # "©"
html.unescape("©")   # "©"

NCRs vs. Named References vs. Direct Characters

In modern UTF-8 documents, direct characters are preferred. NCRs remain valuable in legacy ASCII environments and when generating HTML programmatically.

Quick Facts