literals

来源： https://stackoverflow.com/questions/22204586/literals-vs-immediate-operands

来源： https://stackoverflow.com/questions/42591486/how-we-can-write-binary-octal-and-hexadecimal-literals-of-floating-point-number

问题 Edit: I have reformatted the post to be clearer. Why does this work: struct A {}; struct B { B(A){} }; void operator+(const B&, const B&) {} int main() { A a1, a2; a1 + a2; } and this does not? struct B { B(const char*){} }; void operator+(const B&, const B&) {} //error: invalid operands of types 'const char [6]' and 'const char [6]' to binary 'operator+'| int main() { "Hello" + "world"; } Essentially, in the first example a1 and a2 both convert to B objects through the implicit conversion

问题 Any String literal in Java is a constant object of type String and gets stored in the String literal pool. Will String literals passed as arguments to the methods also get stored in the String literal pool? For example when we write, System.out.println("Hello"); OR anyobj.show("Hello"); will a String "Hello" be created and stored in the String literal pool? Is there any way to print the contents of the String literal pool? 回答1: Every time you use a String literal in your code (no matter where

问题 Any String literal in Java is a constant object of type String and gets stored in the String literal pool. Will String literals passed as arguments to the methods also get stored in the String literal pool? For example when we write, System.out.println("Hello"); OR anyobj.show("Hello"); will a String "Hello" be created and stored in the String literal pool? Is there any way to print the contents of the String literal pool? 回答1: Every time you use a String literal in your code (no matter where

问题 Wikipedia says: For example, the decimal number 0.1 is not representable in binary floating-point of any finite precision However, in C# string s = 0.1.ToString(CultureInfo.InvariantCulture); Console.WriteLine(s); writes 0.1 . I would have expected something like 0.099999999999999999 or so. I am looking for at least one example double literal that is not exactly representable as a double. Edit: As others have pointed out, 0.1 is indeed the literal I have been looking for, as the following

问题 I understand the host of issues in comparing floats, and lament their use in this case - but I'm not the table author and have only a small hurdle to climb... Someone has decided to use floats as you'd expect GUIDs to be used. I need to retrieve all the records with a specific float value. sp_help MyTable -- Column_name Type Computed Length Prec -- RandomGrouping float no 8 53 Here's my naive attempt: --yields no results SELECT RandomGrouping FROM MyTable WHERE RandomGrouping = 0

问题 Is there a way to specify expected integer outcomes in a docstring in hex notation? def identity(val): """ >>> identity(243) 243 >>> identity(243) 0xf3 """ return val if __name__ == "__main__": import doctest doctest.testmod() Doctest doesn't interpret the hex notation, resulting in a failure: ********************************************************************** File "hextest.py", line 5, in __main__.identity Failed example: identity(243) Expected: 0xf3 Got: 243 *****************************

问题 In Go, a sync.Mutex or chan is used to prevent concurrent access of shared objects. However, in some cases I am just interested in the latest value of a variable or field of an object. Or I like to write a value and do not care if another go-routine overwrites it later or has just overwritten it before. Update: TLDR; Just don't do this. It is not safe. Read the answers, comments, and linked documents! Here are two variants good and bad of an example program, where both seem to produce

问题 I need some help figuring out how to execute this python code from python -c I am have trouble formatting python so that it will execute for another app in cmd I understand there maybe other ways to do what I am doing but I am limited by the final execution using cmd python -c so please keep this in mind. So I have some python code ie, import os import shutil myPath =r"C:\dingdongz" for root, dirs, files in os.walk(myPath): for file in files: os.remove(os.path(root, file)) for dir in dirs: