flags

Why should I never use 0 in a flag enum [duplicate]

由 喜你入骨 提交于 2020-06-12 07:32:30
问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Should an Enum start with a 0 or a 1? Why should I never use 0 in a flag enum? I have read this multiple times now and would like to know the reason :) 回答1: Because Flag enums are bit collections, or sets of options. A 0 value would be part of all sets, or of none. It just wouldn't work. 回答2: Why should I never use 0 in a flag enum? The question is predicated on an incorrect assumption. You should always use

c++ fstream - creating own formatting flags

由 大城市里の小女人 提交于 2020-05-29 03:23:34
问题 i need to create new flags for the format of the output file. i have a class class foo{ bar* members; ofstream& operator<<(ofstream&); ifstream& operator>>(ifstream&); }; and i want to use it like: fstream os('filename.xml'); foo f; os << xml << f; os.close(); this will save an xml file. fstream os('filename.json'); foo f; os << json << f; os.close(); and this an json file. How can i do this? 回答1: You can easily create yor own manipulators, either hijacking an existing flag or using std::ios

c++ fstream - creating own formatting flags

由 …衆ロ難τιáo~ 提交于 2020-05-29 03:22:37
问题 i need to create new flags for the format of the output file. i have a class class foo{ bar* members; ofstream& operator<<(ofstream&); ifstream& operator>>(ifstream&); }; and i want to use it like: fstream os('filename.xml'); foo f; os << xml << f; os.close(); this will save an xml file. fstream os('filename.json'); foo f; os << json << f; os.close(); and this an json file. How can i do this? 回答1: You can easily create yor own manipulators, either hijacking an existing flag or using std::ios

c++ fstream - creating own formatting flags

由 跟風遠走 提交于 2020-05-29 03:22:06
问题 i need to create new flags for the format of the output file. i have a class class foo{ bar* members; ofstream& operator<<(ofstream&); ifstream& operator>>(ifstream&); }; and i want to use it like: fstream os('filename.xml'); foo f; os << xml << f; os.close(); this will save an xml file. fstream os('filename.json'); foo f; os << json << f; os.close(); and this an json file. How can i do this? 回答1: You can easily create yor own manipulators, either hijacking an existing flag or using std::ios

setting flags to compiler from eclipse (with gcc)

由 孤街浪徒 提交于 2020-05-17 06:41:25
问题 It seems I'm still a newbie in eclipse, and I need to set some compilation flags to my ANSI C project with the gcc compiler. Such flags are for example.. -std=c99 -Wall -Wconversion -Wtype-limits -pedantic and some more. I remember not so long ago, I used to set that flags from a very intuitive interface with check-boxes and labels, but it is not any more there... for example in this link: Enabling flags (Wall, pedantic) for C/C++ compilation within Eclipse they are making a very similar

How to print combined Flag in the same way as name property

由 送分小仙女□ 提交于 2020-03-23 07:16:42
问题 In Python, you can use the Flag class to represent combinations of values. class Color(Flag): Red = auto() Green = auto() Blue = auto() White = Red | Green | Blue These implicitly convert to strings so you can print them. >>> print(Color.Red, Color.White, Color.Red|Color.Green) Color.Red Color.White Color.Green|Red The name property gives you can even nicer way to print, but it doesn't work for unnamed combined values. >>> print(Color.Red.name, Color.White.name, (Color.Red|Color.Green).name)

Intent to start activity - but don't bring to front

由 ╄→гoц情女王★ 提交于 2020-03-17 06:44:04
问题 Description: Activity A is visible (or in the background) Intent I is received by a broadcast with valuable extras and then passes the extras to a new Intent I2 that will be used to start activity A . Outcome: Do not bring activity to front if activity is in background. Code: Intent I2= new Intent(context, MyActivity.class); I2.putExtra(.. I2.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK); // | Intent.FLAG_ACTIVITY_NEW_TASK); context.startActivity(I2); Note: I added no "android:taskAffinity" to

How to add flags with my intent in the manifest file

由 ≡放荡痞女 提交于 2020-02-27 04:30:50
问题 we know that there are flags which we can add to our intent using the addFlags() method in our java code. Is there any way we can add these flags in the manifest file itself instead of writing this in java code. I need to add REORDER_TO_FRONT flag for one of my activities in the manifest. How to achieve this ? 回答1: In manifest file you can not add Intent flags.You need to set the flag in Intent which u pass to startActivity. Here is a sample: Intent intent = new Intent(this,

Python中正则表达式用法 重点

由 我只是一个虾纸丫 提交于 2020-02-26 15:53:12
Python中正则表达式基础知识 </h1> <div class="clear"></div> <div class="postBody"> 一、正则表达式 　　1.使用正则表达式的动机 　　　　1. 文本处理已经成为计算机常见工作之一 　　　　2. 对文本内容的搜索，定位，提取是逻辑比较复杂的工作 　　　　3. 为了快速方便的解决上述问题，产生了正则表达式技术 　　2.定义： 　　　　即文本的高级匹配模式，提供搜索，替换等功能。其本质是由一系列字符和特殊符号构成的字串，这个字串即正则表达式。 　　3.原理： 　　　　通过普通字符和有特定含义的字符，来组成字符串，用以描述一定的字符串规则，比如：重复，位置等，来表达某类特定的字符串，进而匹配。 　　4.元字符使用： 　　　　1.普通字符--------匹配规则：每个普通字符匹配其对应的字符 　　　　　　e.g. 　　　　　　　　In : re.findall('ab',"abcdefabcd") 　　　　　　　　Out: ['ab', 'ab'] 　　　　注意：正则表达式在python中也可以匹配中文 　　　　2.或关系(|) 　　　　　　元字符: | 　　　　　　匹配规则: 匹配 | 两侧任意的正则表达式即可 　　　　　　e.g. 　　　　　　　　In : re.findall('com|cn',"www.baidu.com

SameSite cookie in Java application

由 假装没事ソ 提交于 2020-02-17 06:58:05
问题 Do you know any Java cookie implementation which allows to set a custom flag for cookie, like SameSite=strict ? It seems that javax.servlet.http.Cookie has a strictly limited set of flags which can be added. 回答1: I am not a JEE expert, but I think that because that cookie property is a somewhat new invention, you cannot expect it to be present in Java EE 7 interfaces or implementations. The Cookie class is missing a setter for generic properties, as it seems. But instead of adding the cookie
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