<p>What would you say if you could use three variables in a for loop when iterating over strings? That is, if you could write</p>
<pre><code>for runeIndex, byteIndex, r := range s {
// code
}
</code></pre>
<p>instead of</p>
<pre><code>runeIndex := 0
for byteIndex, r := range s {
// code
runeIndex++
}
</code></pre>
<p>?</p>
<p>As far as I can see, the proposed syntax wouldn't violate the Go1 compatibility promise, would it?</p>
<hr/>**评论：**<br/><br/>TheMerovius: <pre><p>Honestly: It was a mistake to make range over <code>string</code>s behave differently from <code>[]byte</code>s. It would've been better addressed by building a rune-iterator into unicode/utf8. This way</p>
<ul>
<li>People assume strings will always contain valid utf8, which is false.</li>
<li>People assume iterating over runes is the best thing to do, which is <em>especially</em> false with the last point.</li>
<li>People get confused by the fact, that those two very similar types create such different behavior.</li>
</ul></pre>HectorJ: <pre><p>This would add complexity to the language, just for some minor syntactic sugar.</p></pre>robertmeta: <pre><p>At first blush to me, feels a bit confusing, because the range keyword always returns index, value elsewhere: arrays, slices, maps, strings. The 3 value syntax would <strong>only</strong> be useful with strings seems like. </p></pre>gohacker: <pre><p>Yes, you couldn't use it with arrays, slices and maps, like 2-value syntax cannot be used with channels.</p></pre>robertmeta: <pre><p>Fair point -- actually that makes me withdraw my complaints about it. </p></pre>YEPHENAS: <pre><p>The reason of existence for the index variable in for-range loops is to make it possible to access the current element via the [] operator, but you can't access a position in a string with s[runeIndex].</p></pre>xiegeo: <pre><p>I want range to take an interable interface. Sorry for going of in a tangent.</p></pre>ultra_brite: <pre><p>Don't bother, nobody maintaining Go is interested in community input when it comes to changing the syntax of the language.</p></pre>
