c++ - void *p...; if (p > 0) .... Is this undefined behavior? -


After a compiler upgrade I received a new warning message.

WARNING: Command to compare pointer with integer zero [[VIDEO] 

  if (inx> gt; 0)    
 An indicator that comes out is usually I expect this old code to be 0 or less. It has got me to think about signed and unsigned values ​​and possible risk.  
 Some research shows:  
     
  •   
  •   <
  •   
  •    
     It suggests that an address (returned by malloc) can never be zero  
     which is my old copy of standard.  
     
      4.10 pointer conversion   
     1 single tap indicator constant is an integral static expression (5.1 9) integer type property which evaluates zero A private std :: nullptr_t type or a null pointer constant can be changed into an indicator type; The result is the empty indicator value of that type and separates the object or pointer from the other type of function into the work type. This type of conversion is called a zero-pointer conversion. Compare two similar types of null pointer values. A null pointer constant is an indicator of conversion from an indicator to a CV-quality ad type, rather than an index conversion sequence that happens after the Quillin Quarter Conversions (4.4). The redundant indicator of an integral type can be changed into a type of continuous type: std :: nullptr_t   
     It specifically states that the comparison of two tap signals is the same.  
      Keeping this in mind, is this small piece of code undefined? Or is there another piece of puzzle I am missing?    
     
     
     This is not an undefined behavior, but the result is unspecified if  inx  is not zero.  
     
     C ++ 11 5.9 / 2: If two points point to the P and the same type of different objects, for the same object or element of the same array or for various functions , Or  if only one of them is empty ,  p < q ,  P & gt; q ,  p < = q , and  p & gt; = q   Unspecified .     
     You can make sure that if the conditional code does not execute, if  inx  is zero - but it will not be that it is not zero. It is possible to compare  inx! = 0 , which is well defined if and only if  inx  is non-empty.

Comments

Post a Comment

Popular posts from this blog

c# - ASP.NET MVC - Attaching an entity of type 'MODELNAME' failed because another entity of the same type already has the same primary key value -

In brief, the wrapper module is inserted during posting and the status of an entry is changed to 'modified' . Before changing the state, the state is set to 'separate', but calling attachments () causes the same error to be thrown away. I am using EF 6. Model / wrapper class public class avi model {public A is a {get; Set; } Public listing & lt; B & gt; B {received; Set; } Public cc {receipt; Set; }} Administrator edit public functioning (int? id) {if (id == null) {new HttpStatusCodeResult (HttpStatusCode.BadRequest); } If (! Conveyor Access (id.Value)) new HTTPTitus code result (HTTP status code. Forbidden); Var aViewModel = new AViewModel (); aViewModel.A = db.As.Find (id); If (aViewModel.Receipt == zero) {return HttpNotFound (); } aViewModel.b = db.Bs.Where (x => x.aid == id.Value) .Oolist (); AViewModel.Vendor = db.Cs.Where (x => x.cid == aViewModel.a.cID) .FirstOrDefault (); See Return (aViewModel); } [HTPFost] [Valid AntitiferousTeacon...
Read more

jasper reports - How to center align barcode using jasperreports and barcode4j -

I use iReport 5.5.0 . How to align a barcode component to the center The relevant piece of my jrxml is below & Lt; JR: Code 128 xmlns: JR = "http://jasperreports.sourceforge.net/jasperreports/components" xsi: schemaLocation = "http://jasperreports.sourceforge.net/jasperreports/components http: //jasperreports.sourceforge Purge / xsd / components.xsd "textPosition =" bottom "& gt; & Lt; Jr: codeExpression & gt; & Lt; [CDATA [$ F {number}]] & gt; & Lt; / Jr: codeExpression & gt; & Lt; / Jr: Code 128 & gt; & Lt; / componentElement & gt; "Text" itemprop = "text"> Create a style after this, it is called "barcode", like: & lt; Style name = "barcode" fontName = "Helvetica" fONTSIZE = "10" hAlign = "center" valign = "center" /> and set the property of your barcode element to "barcode".
Read more

django - CommandError: You must set settings.ALLOWED_HOSTS if DEBUG is False -

I use Django 1.6.5 with settings in my program txsite: DEBUG = true I set the lie to debug, but when I get the runner , I get the following error: CommandError: You have to set the settings. OLOWOWHESTS If DEBUG is False I ALLOWED_HOSTS = ['127.0.0.1', 'localhost'] but I get the same error. Does anyone know this address? Try ALLOWED_HOSTS = ['*'] Less secure If you are not on a firewall or public LAN, but what I use and it works. Edit: Interestingly enough, I have to add some of my 1.8 projects, even if DEBUG = True . Why so very uncertain
Read more