在c#中使用pinvoke在64位上调用sprintf和朋友 [英] Using pinvoke in c# to call sprintf and friends on 64-bit
问题描述
在 C# 中使用 pinvoke 调用 _snwprintf 时遇到了一个有趣的问题.它适用于整数类型,但不适用于浮点数.
I am having an interesting problem with using pinvoke in C# to call _snwprintf. It works for integer types, but not for floating point numbers.
这是在 64 位 Windows 上,它在 32 位上运行良好.
This is on 64-bit Windows, it works fine on 32-bit.
我的代码如下,请记住,这是一个人为的示例,用于展示我所看到的行为.
My code is below, please keep in mind that this is a contrived example to show the behavior I am seeing.
class Program
{
[DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
private static extern int _snwprintf([MarshalAs(UnmanagedType.LPWStr)] StringBuilder str, IntPtr length, String format, int p);
[DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
private static extern int _snwprintf([MarshalAs(UnmanagedType.LPWStr)] StringBuilder str, IntPtr length, String format, double p);
static void Main(string[] args)
{
Double d = 1.0f;
Int32 i = 1;
Object o = (object)d;
StringBuilder str = new StringBuilder(32);
_snwprintf(str, (IntPtr)str.Capacity, "%10.1lf", (Double)o);
Console.WriteLine(str.ToString());
o = (object)i;
_snwprintf(str, (IntPtr)str.Capacity, "%10d", (Int32)o);
Console.WriteLine(str.ToString());
Console.ReadKey();
}
}
这个程序的输出是
0.0
1
它应该在第一行打印 1.0 而不是 0.0,到目前为止我被难住了.
It should print 1.0 on the first line and not 0.0, and so far I am stumped.
推荐答案
我不确定为什么您的调用不起作用,但是 这些方法的安全版本在 x86 和 x64 中都可以正常工作.
I'm not exactly sure why your calls do not work, but the secured versions of these methods do work properly in both x86 and x64.
以下代码按预期工作:
class Program
{
[DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
private static extern int _snwprintf_s([MarshalAs(UnmanagedType.LPWStr)] StringBuilder str, IntPtr bufferSize, IntPtr length, String format, int p);
[DllImport("msvcrt.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
private static extern int _snwprintf_s([MarshalAs(UnmanagedType.LPWStr)] StringBuilder str, IntPtr bufferSize, IntPtr length, String format, double p);
static void Main(string[] args)
{
// Preallocate this to a given length
StringBuilder str = new StringBuilder(100);
double d = 1.4;
int i = 7;
float s = 1.1f;
// No need for box/unbox
_snwprintf_s(str, (IntPtr)100, (IntPtr)32, "%10.1lf", d);
Console.WriteLine(str.ToString());
_snwprintf_s(str, (IntPtr)100, (IntPtr)32, "%10.1f", s);
Console.WriteLine(str.ToString());
_snwprintf_s(str, (IntPtr)100, (IntPtr)32, "%10d", i);
Console.WriteLine(str.ToString());
Console.ReadKey();
}
}
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