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问题 void swap(int &first, int &second){ int temp = first; first = second; second = temp; } ////// int a=3,b=2; swap(a,b); In the above example, the C compiler complaints that "void swap(int &first, int &second)" has a syntax error like missing "&" before "( / {". I don't understand why? Doesn't C support this feature? 回答1: C doesn't support passing by reference. So you will need to use pointers to do what you are trying to achieve: void swap(int *first, int *second){ int temp = *first; *first =

问题 void swap(int &first, int &second){ int temp = first; first = second; second = temp; } ////// int a=3,b=2; swap(a,b); In the above example, the C compiler complaints that "void swap(int &first, int &second)" has a syntax error like missing "&" before "( / {". I don't understand why? Doesn't C support this feature? 回答1: C doesn't support passing by reference. So you will need to use pointers to do what you are trying to achieve: void swap(int *first, int *second){ int temp = *first; *first =

问题 Given this magical interface: public interface IHat<out TRabbit> { TRabbit Take(); } And this class hierarchy: public class Rabbit { } public class WhiteRabbit : Rabbit { } I can now compile this: IHat<WhiteRabbit> hat1 = null; IHat<Rabbit> hat2 = hat1; Which is great. But what if I define the interface differently: public interface IHat<out TRabbit> { bool Take(out TRabbit r); } I'm indicating that the hat might be empty, using a separate boolean return value (the previous version would

问题 So I am new to C# and I am having difficulty understanding out . As opposed to just returning something from a function using System; class ReturnTest { static double CalculateArea() { double r=5; double area = r * r * Math.PI; return area; } static void Main() { double output = CalculateArea(); Console.WriteLine("The area is {0:0.00}", output); } } compare to this using System; class ReturnTest { static void CalculateArea(out double r) { r=5; r= r * r * Math.PI; } static void Main() { double

问题 i have a mail template newsletter here: http://www.newsletter.vendopor.com/m29-04-13/index2.html But at the end, have a paragraph that contains that text: Por favor, envía este correo a las personas que creas le puede ayudar nuestro... And this text, go out the paragraph (i have a width 380 attribute in css and keeps going out). It's at the end of the page I've searched in google, but can't find the solution Works fine on Chrome, but in Mozilla (last version) the text is going out. Thanks a

问题 I'm trying to create a procedure that will enter data and then return a message in the OUT parameter, however i'm getting this message "argument 5 for routine hospital.alextest10 is not a variable or NEW pseudo-variable in BEFORE trigger" i have this as my procedure: create procedure alextest10 (IN a_patid CHAR(3), IN a_patnam VARCHAR(12), IN a_consno CHAR(3), IN a_ward CHAR(2), OUT a_message VARCHAR(50)) BEGIN set a_message = 'Database updated'; INSERT INTO patient (patient_id, patient_name,

问题 What is the effect of SYSO - System.out.println() ? If my computer is executing a large job such as fetching 2 Lakhs (approximately 2,000,000) records from a database to a file, does SYSO affect the execution time? 回答1: Of course it affects it. Every operation comes with a cost. Writing to system out is IO, and comes with a non-negligible cost. To know the exact effect on your program, there's no other solution than benchmarking: run the program with and without the println calls, and measure

问题 any idea why when i zoom out website 4div always go down to next line. Demo: http://autovin.org/tp/ /* Reset All Styles */ * {padding:0px; margin:0px;font-family:Segoe UI;} /* Background */ body {background:url(images/grids.gif) white;} /* Wrapper */ .wrapper {width:998px;margin:0 auto;} /* Header */ .header {padding:20px 0 20px 0;} /* Navigation */ .nav {background:#82b2c9;color:white;} /* Content */ .content {padding:10px 0;overflow:hidden;} /* Box */ .box {width:240px; margin:0 10px 10px 0

问题 This question already has an answer here : Are P/Invoke [In, Out] attributes optional for marshaling arrays? (1 answer) Closed 3 years ago . I've seen both when looking up P/Invoke definitions... sometimes [Out] is used, and sometimes out ... I'm assuming they're the same. 回答1: They are the equivalent to each other when used in the context of P/Invoke - see OutAttribute. You can apply the OutAttribute to value and reference types passed by reference to change In/Out behavior to Out-only

问题 I am working on Ubuntu 11.10 Local branch of my git-repo is up to date I then wrote following command in terminal: heroku create --stack cedar and it said: Notice: on Wed, 20 June, our default stack will change to Cedar. http://bit.ly/Lh0rM5 Creating radiant-wind-7413... done, stack is cedar http://radiant-wind-7413.herokuapp.com/ | git@heroku.com:radiant-wind-7413.git Git remote heroku added All fine till now, then I typed following in terminal: git push heroku master and the following error