22 lines
2.6 KiB
XML
22 lines
2.6 KiB
XML
<?xml version="1.0"?>
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<clause number="12.3.3.23" title="&& expressions">
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<paragraph>For an expression expr of the form expr-first && expr-second: <list><list_item> The definite assignment state of v before expr-first is the same as the definite assignment state of v before expr. </list_item><list_item> The definite assignment state of v before expr-second is definitely assigned if the state of v after expr-first is either definitely assigned or "definitely assigned after true expression". Otherwise, it is not definitely assigned. </list_item><list_item> The definite assignment state of v after expr is determined by: </list_item><list><list_item> If the state of v after expr-first is definitely assigned, then the state of v after expr is definitely assigned. </list_item><list_item> Otherwise, if the state of v after expr-second is definitely assigned, and the state of v after expr-first is "definitely assigned after false expression", then the state of v after expr is definitely assigned. </list_item><list_item> Otherwise, if the state of v after expr-second is definitely assigned or "definitely assigned after true expression", then the state of v after expr is "definitely assigned after true expression". </list_item><list_item> Otherwise, if the state of v after expr-first is "definitely assigned after false expression", and the state of v after expr-second is "definitely assigned after false expression", then the state of v after expr is "definitely assigned after false expression". </list_item><list_item> Otherwise, the state of v after expr is not definitely assigned. </list_item></list></list></paragraph>
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<paragraph>
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<example>[Example: In the example <code_example><![CDATA[
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class A
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{
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static void F(int x, int y) {
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int i;
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if (x >= 0 && (i = y) >= 0) {
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// i definitely assigned
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}
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else {
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// i not definitely assigned
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}
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// i not definitely assigned
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}
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}
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]]></code_example>the variable i is considered definitely assigned in one of the embedded statements of an if statement but not in the other. In the if statement in method F, the variable i is definitely assigned in the first embedded statement because execution of the expression (i = y) always precedes execution of this embedded statement. In contrast, the variable i is not definitely assigned in the second embedded statement, since x >= 0 might have tested false, resulting in the variable i's being unassigned. end example]</example>
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</paragraph>
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</clause>
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