symbols | 易学教程

Where does the __1 symbol come from when using LLVM's libc++?

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问题 I see a fair amount of questions like Apple Mach-O Linker (Id) Error and Undefined symbols in cryptopp at IOS 64-bit project. The problem is usually described as: Undefined symbols for architecture i386: "std::__1::basic_ostream<char, std::__1::char_traits<char> >::flush()", referenced from: cv::gpu::error(char const*, char const*, int, char const*) in opencv2(gpumat.o) The problem often reduces to mixing/matching -stdlib=libc++ (LLVM C++ runtime) and -stdlib=libstdc++ (GNU C++ runtime). The

Using Ruby Symbols

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问题 First time I tried learning Ruby was 2 years ago, now I have started again. The reason I stopped was because I could not understand the Symbol class. And now I am at the same point again, completely lost in when and why you use Symbols. I have read the other posts on Stackoverflow as well as Googled for several explanations. But I do not understand it yet. First I thought symbols was just a way to create some sort of "named constant" without having to go through the same process as in let say

R: What are operators like %in% called and how can I learn about them?

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问题 I know the basics like == and != , or even the difference (vaguely) between & and && . But stuff like %in% and %% and some stuff used in the context of sprintf() , like sprintf("%.2f", x) stuff I have no idea about. Worst of all, they're hard to search for on the Internet because they're special characters and I don't know what they're called... 回答1: There are several different things going on here with the percent symbol: Binary Operators As several have already pointed out, things of the

Ubuntu and undefined symbol for SSLv2_method

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问题 Is Canonical renaming symbols in their package version of openssl, and if so for what purpose? When I compile openssl-1.0.0e.tar.gz (downloaded from openssl.org directly) from scratch I see the necessary symbol, but Python (and I) can't seem to find it in the packaged version. Read on for more information about how I diagnosed this problem... I am trying to compile Python 2.6.1 on Ubuntu 11.10, and get the error message above. The reason I am using this older Python is that I am trying to

Get the description of a ES6 Symbol

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问题 I wonder if there is a nice way to get the descriptions of a Symbol. For example, var s = Symbol(5); The default implementation of the toString will simply print Symbol(5) I would like to find a way to extract the actual description i.e. 5 回答1: Symbol.description returns description of the symbol. Simply do s.description in your case. REF: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/description 回答2: String(symbol).slice(7, -1) || null This works

printing “<html>” using html

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问题 How do I print the "html" tag, including '<' and '>'? How can I do this for any tag, without using text areas and Javascript? 回答1: Use HTML character references: <html> Should output <html> 回答2: Try doing: <html> 回答3: Special characters in HTML, such as '<', '>', '"' and '&' can be printed using the following format: &name; where name would be replaced by a character name. The most common would then be < = < (less than) > = > (greater than) & = & (ampersand) " = " (double quote) So to write

Is there a known issue relating to Windows 7 Kernel Symbols?

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问题 I have a few Windows 7 machines that I am not able to read their memory dumps. I found something that I suspect may be related, but am not positive: https://twitter.com/aionescu/status/634028737458114560 I also found this: http://support.microsoft.com/kb/2528507 However, the scenario message regarding wow64exts given in the doc is not seen in any of my dumps. I also cannot apply that hotfix at this time to test it. So I'm just looking for some more information or opinions. I'm able to open

Is there a known issue relating to Windows 7 Kernel Symbols?

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When to use symbols instead of strings in Ruby?

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问题 If there are at least two instances of the same string in my script, should I instead use a symbol? 回答1: TL;DR A simple rule of thumb is to use symbols every time you need internal identifiers. For Ruby < 2.2 only use symbols when they aren't generated dynamically, to avoid memory leaks. Full answer The only reason not to use them for identifiers that are generated dynamically is because of memory concerns. This question is very common because many programming languages don't have symbols,

Print and Export to USB (File Format: XML/CSV/Excel) Functionality in Smart device[Symbo Motoroal MC75(Windows Mobile 6.1)] application?

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问题 I have a form which contains combo boxes, textboxes and a data grid with many rows. I want to take print out (with generated barcode [application generating barcode as image]) and also want to export the data in that page as CSV/XML/Excel format to USB or Phone's Physical Directory. Please guide me how to it. This is my first Windows Mobile app. I am not so wise in Windows Mobile. Please help me find a better solution as a code or link or just direct me. 回答1: To create the Print Out, you will