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D样式数组到C样式数组

[英]D Style Arrays to C Style Arrays

原文 2013-12-14 22:36:46 9 2 arrays/ pointers/ d

I am creating a Window in D, and the CreateWindowA function requires pointers to characters, C character arrays basically. 我正在D中创建一个Window，并且CreateWindowA函数需要指向字符（基本上是C字符数组）的指针。

How do I convert a D style array ( char[] ) to a C style array ( char* )? 如何将D样式数组（ char[] ）转换为C样式数组（ char* ）？

2 个解决方案

The two functions to look at are normally std.string.toStringz and std.utf.toUTFz . 通常std.string.toStringz的两个函数是std.string.toStringz和std.utf.toUTFz 。

toStringz will convert string to immutable(char)* , which you can pass to a C function which takes const char* . toStringz会将string转换为immutable(char)* ，您可以将其传递给采用const char*的C函数。 If it can determine that the string is null-terminated (which usually is only the case for string literals, which have a null terminator one passed their end), then it won't allocate and will just use the string 's ptr property, but in most cases, it will allocate. 如果它可以确定string以null终止（通常只有字符串文字，这种情况的末尾有一个null终止符），则它不会分配，而只会使用string的ptr属性，但在大多数情况下，它将分配。

toUTFz will convert from any string type to any character pointer type. toUTFz将从任何字符串类型转换为任何字符指针类型。 It's probably most frequently used for converting to const(wchar)* for Windows, since all of the W functions for Windows take UTF-16, but it can also be used to convert to char* - eg str.toUTFz!(char*)() . 由于Windows的所有W函数都采用UTF-16，因此它可能最常用于Windows的const(wchar)*转换，但是它也可以用于转换为char* -例如str.toUTFz!(char*)() 。 Like toStringz , it will try not to allocate if it can determine that it's unnecessary, but it's almost always necessary. 像toStringz一样，如果它可以确定不必要，它将尝试不分配，但几乎总是必需的。

Now, for your particular case, you're trying to use one of the A functions in Windows. 现在，对于您的特殊情况，您尝试使用Windows中的A函数之一。 This is almost always a bad idea, and I would strongly advise against it. 这几乎总是一个坏主意，我强烈建议不要这样做。 Use toUTFz to convert your string to const(wchar)* and pass that to CreateWindowW . 使用toUTFz将您的string转换为const(wchar)*并将其传递给CreateWindowW 。 AFAIK, the only advantage to the A functions is that they work with pre-Win2K. AFAIK， A函数的唯一优点是它们可与Win2K之前的版本一起使用。 Everything else about them is worse. 关于他们的其他一切都更糟。 However, if for some reason, you insist on using the A functions, then you're going to have to use std.windows.charset.toMBSz , because the A functions don't take UTF-8 but rather the "Windows 8-bit character set," and toMBSz will convert the string to that format. 但是，如果由于某种原因坚持使用A函数，则将不得不使用std.windows.charset.toMBSz ，因为A函数使用的不是UTF-8，而是使用“ Windows 8-位字符集”和toMBSz会将字符串转换为该格式。

you grab the ptr field of the D array. 您可以获取D数组的ptr字段。 and the length field to grab the length 和length字段来获取长度

however if you need a C-style string then you need the toStringz method that will add the null terminator and return the pointer to the first char. 但是，如果需要C样式的字符串，则需要toStringz方法，该方法将添加空终止符并将指针返回第一个字符。 k eep a reference to it if the api doesn't create it's own copy to operate on to avoid dangling pointers by GC k EEP一个它的参考，如果API不创建它自己的拷贝操作，以避免由GC悬摆指针