standards

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 9 years ago . Very simple question, but I want to start using a consistent naming convention for validation methods and I can't think of the best

问题 Why do browser vendors make their own css properties, even they know these properties will not pass the w3c validation before approved and added by w3c? What is the purpose? Is for their own testing, or for web developers, or to demonstrate browser capabilities to the world and to the W3C organizations and to CSS development team of W3C? is it like a beta version of demonstration? if i use any browser specific for now can they remove that property's support from future versions.will i have to

问题 In paragraph 12 of [intro.execution] in the current (C++ 17) C++ standard draft there is written: A full-expression is: [...] an expression that is not a subexpression of another expression and that is not otherwise part of a full-expression. If a language construct is defined to produce an implicit call of a function, a use of the language construct is considered to be an expression for the purposes of this definition. [...] The "use of the language construct" wording refers to the fact that

问题 This answer states that in Java the maximum number of fields an object may have is 65536. Is there any such limit imposed on an object in C++? 回答1: C++03 standard, Annex B (implementation quantities): Because computers are finite, C++ implementations are inevitably limited in the size of the programs they can successfully process. Every implementation shall document those limitations where known. This documentation may cite fixed limits where they exist, say how to compute variable limits as

问题 The signedness of char is not standardized. Hence there are signed char and unsigned char types. Therefore functions which work with single character must use the argument type which can hold both signed char and unsigned char (this type was chosen to be int ), because if the argument type was char , we would get type conversion warnings from the compiler (if -Wconversion is used) in code like this: char c = 'ÿ'; if (islower((unsigned char) c)) ... warning: conversion to ‘char’ from ‘unsigned

问题 The signedness of char is not standardized. Hence there are signed char and unsigned char types. Therefore functions which work with single character must use the argument type which can hold both signed char and unsigned char (this type was chosen to be int ), because if the argument type was char , we would get type conversion warnings from the compiler (if -Wconversion is used) in code like this: char c = 'ÿ'; if (islower((unsigned char) c)) ... warning: conversion to ‘char’ from ‘unsigned

问题 I'm using VS 2010, and I'm wondering how I can get my c++ program to read a file using standard input while debugging. I know how to do it from command prompt, but not when debugging. Basically I want it to read in a file with cin>> instead of me typing stuff - but in debug mode. 回答1: If you go into the project's Properties, under Debugging there's a set of options for how to actually launch the process. IIRC the way to do this is to put: < yourfile.txt In the Command Arguments box. 回答2: I've

问题 Is there a standard on SQL implementaton for multiple calls to the same aggregate function in the same query? For example, consider the following example, based on a popular example schema: SELECT Customer,SUM(OrderPrice) FROM Orders GROUP BY Customer HAVING SUM(OrderPrice)>1000 Presumably, it takes computation time to calculate the value of SUM(OrderPrice). Is this cost incurred for each reference to the aggregate function, or is the result stored for a particular query? Or, is there no

问题 I have searched for this information both on SO and on google, but have not found any authoritative answer. When you have an update statement like: UPDATE table SET rowA = rowB, rowB = NULL ... It seems that: ordering is not important ( UPDATE table SET rowB = NULL, rowA = rowB ) nonetheless, the result is that rowA takes the prev value in rowB, because it seems that UPDATE first reads the previous values, then it updates them. I would like to know if the two above points are true in general

问题 Does C++ standard guarantee the following?: template<typename T> void function(T (&)[1]); template<typename T> void function(T*); int a[1]; function(a); // first function gets called, not second version 回答1: Yes, this is guaranteed, but the reason is different than what GMan says. The "array of length 1" overload will be selected because it is more specialized than the second in template functions partial order. Basically, it means that an argument in the form T(&)[1] will always match the