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string range

R=rsc
DELTA=22  (19 added, 0 deleted, 3 changed)
OCL=34463
CL=34463
This commit is contained in:
Rob Pike 2009-09-08 17:11:57 -07:00
parent 32aa5be6ef
commit c77c3b0196

View File

@ -489,10 +489,10 @@ and <code>while</code> and there is no <code>do-while</code>.
There are three forms, only one of which has semicolons:
</p>
<pre>
// Like a C for:
// Like a C for
for init; condition; post { }
// Like a C while:
// Like a C while
for condition { }
// Like a C for(;;)
@ -521,10 +521,29 @@ for key, value := range m { // key is unused; could call it '_'
}
</pre>
<p>
For strings, the <code>range</code> does more of the work for you, breaking out individual
characters by parsing the UTF-8 (erroneous encodings consume one byte and produce the
replacement rune U+FFFD). The loop
</p>
<pre>
for pos, char := range "日本語" {
fmt.Printf("character %c starts at byte position %d\n", char, pos)
}
</pre>
<p>
prints
</p>
<pre>
character 日 starts at byte position 0
character 本 starts at byte position 3
character 語 starts at byte position 6
</pre>
<p>
Finally, since Go has no comma operator and <code>++</code> and <code>--</code>
are statements not expressions, if you want to run multiple variables in a <code>for</code>
you can use parallel assignment:
you should use parallel assignment:
</p>
<pre>
// Reverse a