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发表于 2018-11-10 15:42:12
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本帖最后由 菜鸟萌新 于 2018-11-10 17:11 编辑 * N1 {" M5 Y+ c4 ?
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The interesting (to me, anyway) part of this question is that the do-variable in an io-implied-do does NOT have "statement scope" the way a DATA implied-do or array constructor implied-do variable do. With statement scope, the implied-do variable is a new, different variable that inherits only the type of any outer-scope variable (but that type must be integer.)The "i" in the I/O implied DO is the same variable as the line 1 DO control variable and ifort is absolutely correct in complaining about this., pgf90 could support this as an extension, but would need to have the ability to diagnose it (perhaps through a standards checking switch), or else risk being a nonconforming implementation.
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The other interesting part is that we do, sort-of, allow changing DO variables, as an extension, but you have to do it by passing the variable to a procedure which then changes it. ifort recognizes the possibility and generates an explicit test rather than a loop count if it sees this.1 H! Y/ k- G0 s7 _& t
7 ^0 b" ^0 K, O* O1 S l这个问题的有趣(对我来说,无论如何)部分是io声明的do中的do的变量没有DATA声明的方式或者数组构造函数声明-do变量的方式。 对于语句范围,声明do变量是一个新的,不同的变量,它只继承任何外部作用域变量的类型(但该类型必须是整数。)I / O暗示DO中的“i”是相同的变量 作为第1行DO控制变量和ifort在抱怨这一点时绝对正确。,pgf90可以支持这作为扩展,但是需要能够诊断它(可能通过标准检查开关),否则冒险成为 不合格的实施。& `* o/ A; X v# M7 L( j1 ]1 p
; G" i% f1 L; o4 _" z$ M另一个有趣的部分是我们这样做,排序,允许更改DO变量,作为扩展,但你必须通过将变量传递给一个程序然后更改它来完成它。 如果它看到这个,ifort会识别出这种可能性并生成一个显式测试而不是一个循环计数。5 D/ p& m, o q+ T- O
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