Display the source code in std/utf.d from which this page was generated on github.

If you spot a problem with this page, click here to create a Bugzilla issue.

Quickly fork, edit online, and submit a pull request for this page. Requires a signed-in GitHub account. This works well for small changes. If you'd like to make larger changes you may want to consider using local clone.

Function `std.utf.decode`

Decodes and returns the code point starting at str[index]. index is advanced to one past the decoded code point. If the code point is not well-formed, then a UTFException is thrown and index remains unchanged.


						
				dchar decode(Flag!("useReplacementDchar") useReplacementDchar = No.useReplacementDchar, S)
				(
				

				  auto ref S str,
				

				  ref size_t index
				

				)
				

				if (!isSomeString!S && isRandomAccessRange!S && hasSlicing!S && hasLength!S && isSomeChar!(ElementType!S));
				

				

				dchar decode(Flag!("useReplacementDchar") useReplacementDchar = No.useReplacementDchar, S)
				(
				

				  auto scope ref S str,
				

				  ref size_t index
				

				) pure @trusted
				

				if (isSomeString!S);

decode will only work with strings and random access ranges of code units with length and slicing, whereas decodeFront will work with any input range of code units.

Parameters

Name	Description
useReplacementDchar	if invalid UTF, return replacementDchar rather than throwing
str	input string or indexable Range
index	starting index into s[]; incremented by number of code units processed

Returns

decoded character

Throws

UTFException if str[index] is not the start of a valid UTF sequence and useReplacementDchar is No.useReplacementDchar

Example

size_t i;

assert("a".decode(i) == 'a' && i == 1);
i = 0;
assert("å".decode(i) == 'å' && i == 2);
i = 1;
assert("aå".decode(i) == 'å' && i == 3);
i = 0;
assert("å"w.decode(i) == 'å' && i == 1);

// ë as a multi-code point grapheme
i = 0;
assert("e\u0308".decode(i) == 'e' && i == 1);
// ë as a single code point grapheme
i = 0;
assert("ë".decode(i) == 'ë' && i == 2);
i = 0;
assert("ë"w.decode(i) == 'ë' && i == 1);

Authors

Walter Bright and Jonathan M Davis

License

Boost License 1.0.