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for loops
comment out incomplete stuff R=rsc DELTA=61 (58 added, 0 deleted, 3 changed) OCL=34278 CL=34281
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@ -361,7 +361,7 @@ for one-line <code>funcs</code> and the like:
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</p>
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<pre>
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func CopyInBackground(src, dst chan Item) {
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func CopyInBackground(dst, src chan Item) {
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go func() { for { dst <- <-src } }()
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}
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</pre>
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@ -385,7 +385,7 @@ case a > b:
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</pre>
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<p>
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The grammar admits an empty statement after any statement list, which
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The grammar accepts an empty statement after any statement list, which
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means a terminal semicolon is always OK. As a result,
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it's fine to put semicolons everywhere you'd put them in a
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C program—they would be fine after those return statements,
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@ -480,6 +480,59 @@ codeUsing(f, d);
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</pre>
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<h3 id="for">For</h3>
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<p>
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The Go <code>for</code> loop is similar to—but not the same as—C's.
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It unifies <code>for</code>
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and <code>while</code> and there is no <code>do-while</code>.
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There are three forms, only one of which has semicolons:
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</p>
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<pre>
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// Like a C for:
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for init; condition; post { }
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// Like a C while:
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for condition { }
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// Like a C for(;;)
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for { }
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</pre>
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<p>
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Short declarations make it easy to declare the index variable right in the loop:
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</p>
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<pre>
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sum := 0;
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for i := 0; i < 10; i++ {
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sum += i
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}
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</pre>
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<p>
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If you're looping over an array, slice, string, or map a <code>range</code> clause can set
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it all up for you:
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</p>
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<pre>
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var m map[string] int;
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sum := 0;
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for key, value := range m { // key is unused; could call it '_'
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sum += value
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}
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</pre>
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<p>
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Finally, since Go has no comma operator and <code>++</code> and <code>--</code>
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are statements not expressions, if you want to run multiple variables in a <code>for</code>
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you can use parallel assignment:
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</p>
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<pre>
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// Reverse a
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for i, j := 0, len(a)-1; i < j; i, j = i+1, j-1 {
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a[i], a[j] = a[j], a[i]
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}
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</pre>
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<h3 id="switch">Switch</h3>
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<p>
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@ -546,6 +599,9 @@ func Compare(a, b []byte) int {
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}
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</pre>
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<h2>More to come</h2>
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<!---
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<h2 id="functions">Functions</h2>
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<h3 id="omit-wrappers">Omit needless wrappers</h3>
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@ -917,6 +973,8 @@ Consistency about little things
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lets readers concentrate on big ones.
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</p>
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-->
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</div>
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</body>
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</html>
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