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Function std.utf.toUCSindex

Given index into str and assuming that index is at the start of a UTF sequence, toUCSindex determines the number of UCS characters up to index. So, index is the index of a code unit at the beginning of a code point, and the return value is how many code points into the string that that code point is.

size_t toUCSindex(C) (
  const(C)[] str,
  size_t index
) pure @safe
if (isSomeChar!C);


writeln(toUCSindex(`hello world`, 7)); // 7
writeln(toUCSindex(`hello world`w, 7)); // 7
writeln(toUCSindex(`hello world`d, 7)); // 7

writeln(toUCSindex(`Ma Chérie`, 7)); // 6
writeln(toUCSindex(`Ma Chérie`w, 7)); // 7
writeln(toUCSindex(`Ma Chérie`d, 7)); // 7

writeln(toUCSindex(`さいごの果実 / ミツバチと科学者`, 9)); // 3
writeln(toUCSindex(`さいごの果実 / ミツバチと科学者`w, 9)); // 9
writeln(toUCSindex(`さいごの果実 / ミツバチと科学者`d, 9)); // 9


Walter Bright and Jonathan M Davis


Boost License 1.0.