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go_spec: allow copy() to copy bytes from a string into a []byte

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(language change as discussed a while ago)

R=iant, ken2, r, rsc
CC=golang-dev
https://golang.org/cl/2716041
This commit is contained in:
Robert Griesemer 2010-10-25 16:41:06 -07:00
parent 079cbddbd8
commit 425bbadd3c
1 changed files with 11 additions and 5 deletions
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16
doc/go_spec.html
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@ -1,5 +1,5 @@
<!-- title The Go Programming Language Specification -->
<!-- subtitle Version of Oct 21, 2010 -->
<!-- subtitle Version of Oct 25, 2010 -->
<!--
TODO
@ -4534,13 +4534,17 @@ The built-in function <code>copy</code> copies slice elements from
a source <code>src</code> to a destination <code>dst</code> and returns the
number of elements copied. Source and destination may overlap.
Both arguments must have <a href="#Type_identity">identical</a> element type <code>T</code> and must be
<a href="#Assignability">assignable</a> to a slice
of type <code>[]T</code>. The number of arguments copied is the minimum of
<a href="#Assignability">assignable</a> to a slice of type <code>[]T</code>.
The number of arguments copied is the minimum of
<code>len(src)</code> and <code>len(dst)</code>.
As a special case, <code>copy</code> also accepts a destination argument assignable
to type <code>[]byte</code> with a source argument of a string type.
This form copies the bytes from the string into the byte slice.
</p>
<pre class="grammar">
copy(dst, src []T) int
copy(dst []byte, src string) int
</pre>
<p>
@ -4550,8 +4554,10 @@ Examples:
<pre>
var a = [...]int{0, 1, 2, 3, 4, 5, 6, 7}
var s = make([]int, 6)
n1 := copy(s, a[0:]) // n1 == 6, s == []int{0, 1, 2, 3, 4, 5}
n2 := copy(s, s[2:]) // n2 == 4, s == []int{2, 3, 4, 5, 4, 5}
var b = make([]byte, 5)
n1 := copy(s, a[0:]) // n1 == 6, s == []int{0, 1, 2, 3, 4, 5}
n2 := copy(s, s[2:]) // n2 == 4, s == []int{2, 3, 4, 5, 4, 5}
n3 := copy(b, "Hello, World!") // n3 == 5, b == []byte("Hello")
</pre>
<h3 id="Complex_numbers">Assembling and disassembling complex numbers</h3>