tostring | 易学教程

What's the difference between std::to_string, boost::to_string, and boost::lexical_cast<std::string>?

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问题 What's the purpose of boost::to_string (found in boost/exception/to_string.hpp ) and how does it differ from boost::lexical_cast<std::string> and std::to_string ? 回答1: std::to_string, available since C++11, works on fundamental numeric types specifically. It also has a std::to_wstring variant. It is designed to produce the same results that sprintf would. You may choose this form to avoid dependencies on external libraries/headers. The throw-on-failure function boost::lexical_cast<std::string

Do any Java libraries use annotations for code generation?

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问题 Is anyone aware of a library that uses the the techniques (annotations and classworking) described in this article for automatically generating the standard Object methods toString(), equals() and hashcode() for standard java classes? 回答1: Yes, project Lombok does this. See http://projectlombok.org . It not only supports javac, but also Eclipse. So the methods are not in the source code, but are displayed in the outline view. 回答2: I certainly haven't seen this and I'm not really sure what

How can I have toString() return a multi-line string?

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I'm working on a program that searches through an array and finds the smallest value and then prints out the time, firstName, and lastName of the runner. What I need to figure out is how to return the three values on separate lines, something like: public String toString() { return String.format( firstName + " " + lastName + " " + Time ); } That's what I have right now Is there a way to have the three values print out on separate lines? prashant thakre Try This public String toString(){ return String.format( firstName + ".%n " + lastName + ".%n " + Time); String.format("%s%n%s%n%s", firstName,

c# decimal toString() conversion with comma(,)

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问题 c# decimal.toString() conversion problem Example: I have a value in decimal(.1) when I convert decimal to string using toString() it returns (0,10). Instead of .(DOT) it returns ,(COMMA). 回答1: I believe this is to do with the culture/region which your operating system is set to. You can fix/change the way the string is parsed by adding in a format overload in the .ToString() method. For example decimalValue.ToString(CultureInfo.InvariantCulture); 回答2: For this to be happening, the thread's

A template class in C++

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What is the function of the following C++ template class? I'm after line by line annotations: template<class T> string toString(const T& t, bool *ok = NULL) { ostringstream stream; stream << t; if(ok != NULL) *ok = stream.fail() == false; return stream.str(); } Is it like Java's toString() method? Basically, it will take any object which has an operator<< defined for output to a stream, and converts it to a string. Optionally, if you pass the address of a bool varaible, it will set that based on whether or not the conversion succeeeded. The advantage of this function is that, once defined, as

javascript对象类型判断

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#####1.使用typeof操作符 typeof操作符号的作用是返回一个用于只是其操作对象类型的字符串。语法如下： typeof val val 参数作为一个表达式，代表了javascript中的对象类型或基本数据类型， typeof 运算会返回该对象或基本数据类型的字符串描述。 typeof 根据操作对象和对应的类型描述字符串，包括以下几种： <table class="standard-table"> <thead> <tr> <th scope="col">操作对象或基本数据类型</th> <th scope="col">类型描述字符串</th> </tr> </thead> <tbody> <tr> <td>Undefined</td> <td><code>"undefined"</code></td> </tr> <tr> <td>Null</td> <td><code>"object"</code></td> </tr> <tr> <td>Boolean</td> <td><code>"boolean"</code></td> </tr> <tr> <td>Number</td> <td><code>"number"</code></td> </tr> <tr> <td>String</td> <td><code>"string"</code></td> </tr>

JPA: java.lang.StackOverflowError on adding toString method in entity classes

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Everything worked fine until I added toSting() in my entity classes. After which I start getting the following error in runtime: Exception in thread "main" java.lang.StackOverflowError at java.lang.AbstractStringBuilder.append(Unknown Source) at java.lang.StringBuilder.append(Unknown Source) at java.lang.StringBuilder.<init>(Unknown Source) at entity.Guide.toString(Guide.java:51) at java.lang.String.valueOf(Unknown Source) at java.lang.StringBuilder.append(Unknown Source) at entity.Student.toString(Student.java:45) ... @Entity public class Teacher { @Id @GeneratedValue(strategy=GenerationType

ES6深入浅出-7 新版的类（上集）-1.介绍原型

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ES6新出的关键class BE受雇与网景开发了JS 当我们在写一个对象的时候，我们实际上内存的形式表示。 obj等于一个空对象，可以直接toString。它为什么可以有toString window是一个全局的对象。 window下有个object的属性。通过window.Object.prototype找到了toString 为了方便理解，当说原型的时候先理解为共用属性。 toString是很多对象的共用属性。当谢var obj为一个空对象的时候，为什么可以获取到toString的方法呢？？？当你写这个空对象的时候，因为js做了一个特殊的逻辑每一个对象都会有一个xxx属性指向它的原型，当访问obj.toString的时候。这个xxx就起作用了。实际上调用的是409的toString 这样可以做到代码复用。再声明一个obj2同样可以用到toString 数组的toString是怎么拿到这个123的为什么不同的对象调用同一个toString，得到不同的结果当写obj.toString等价于写obj.toString.call(obj) 。等价call这个参数，并把这个参数传进去。 push的原型是怎么获取到的当调用a.push的时候，会去内存里面所有的对象里面去找这个方法，找到xxx里面，再找到原型里面找到了push方法结束来源： https://www

How to pass variables to overridden toString() method?

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问题 Is it possible to pass in a bool variable into an overridden toString() method, so it can conditionally print the object in different formats? 回答1: You can define overload method of ToString() . public string ToString(bool status){ // } 回答2: The typical pattern for parametrized ToString() is to declare an overload with a string parameter. Example: class Foo { public string ToString(string format) { //change behavior based on format } } For a framework example see Guid.ToString 回答3: If you are

How does Object.toString() get the “memory address” and how can I mimic it

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The toString method of Object is unique in that it seems to be the only place in Java where the memory address is viewable. How does Object do this? I would like to know so that I can mimic its implementation in a class of my own. I can't use super.toString() because I'm extending a class which overrides toString already. Update: The premise of my question asks for the memory address, but the answers have indicated that this premise is incorrect, so what I am actually asking is: How does Object.toString() return what it does, and how can I mimic it? It is not the memory address, it is the