|
Hello everyone,
i am trying to compile my program where i am using the functions like sqrt pow and fabs. I do have math.h included but for some reason i get errors like:
error C2668: 'fabs' : ambiguous call to overloaded function
same for the rest of the functions
i have this included:
#include "stdafx.h"
#include "math.h"
i tried including <cmath> but still same errors.
Does anyone know why they are not being recognized?
my file is .cpp not .c but it is an MFC project.
thanks
|
|
|
|
|
It's because those functions are overloaded for several types: float, double and long double. Thus, if you pass in an integer, the compiler doesn't which one to choose. An easy fix is to simply pass a double (multiply what you pass in by 1.0), this should fix the problem.
int result = (int)fabs(value*1.0);
|
|
|
|
|
Cedric Moonen wrote: int result = (int)fabs(value*1.0);
Better could be
int result = (int)fabs((double)value);
Because it avoids a multiplication. Am I right?
- ns ami -
|
|
|
|
|
Yes you're right. It's just because I am used to multiply by 1.0 because in general I use that in calculation (where I don't want to put a cast inside because it looks ugly) 
|
|
|
|
|
ns ami wrote: Am I right?
Only if the code were in a huge loop would the difference in time even be noticeable.
"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
|
|
|
|
|
it won't matter at all. the multiplication will be optimized away, and the two different calls will end with exactly the same object code.
|
|
|
|
|
nevertheless it's a bad style as many people won't understand it.
Don't try it, just do it! 
|
|
|
|
|
the compiler will optimize that multiplication away.
int value = rand();
int result1 = (int)fabs(value*1.0);
printf("%d, %d\n", result1, result1);
VC6, release mode gives the following assembly:
; 10 : int value = rand();
call _rand
; 11 : int result1 = (int)fabs(value*1.0);
mov DWORD PTR -4+[esp+4], eax
fild DWORD PTR -4+[esp+4]
fabs
call __ftol
; 12 : printf("%d, %d\n", result1, result1);
push eax
push eax
push OFFSET FLAT:??_C@_07JPPP@?$CFd?0?5?$CFd?6?$AA@ ; `string'
call _printf
no fmul.
if you do this:
int value = rand();
int result1 = (int)fabs((double)value);
printf("%d, %d\n", result1, result1);
you get this:
; 10 : int value = rand();
call _rand
; 11 : int result1 = (int)fabs((double)value);
mov DWORD PTR -4+[esp+4], eax
fild DWORD PTR -4+[esp+4]
fabs
call __ftol
; 12 : printf("%d, %d\n", result1, result1);
push eax
push eax
push OFFSET FLAT:??_C@_07JPPP@?$CFd?0?5?$CFd?6?$AA@ ; `string'
call _printf
exactly the same.
|
|
|
|
|
Chris Losinger wrote: the compiler will optimize that multiplication away.
Thank you for pointing out that...
- ns ami -
|
|
|
|
|
i need alternative code for CMap is it possible to implement my own CMap wrapper Class using the STL::map
Hi this Ravinder
|
|
|
|
|
I don't really understand your question but a std::map is an alternative for the MFC CMap (in fact, I much prefer the STL containers than the MFC containers).
|
|
|
|
|
... in addition, perhaps the biggest difference is that CMap uses hashing for its keys, and std::map uses key comparisons to store them in some sorted order.
--
Arman
|
|
|
|
|
Need the wrapper class for CMap using the STL map(Because i have some problems using CMap i want the same functionality of CMap but internally i have to use map)
Hi this Ravinder
|
|
|
|
|
So you need the interface of CMap and the implementation of std::map..? If so, then you need to declare your own CMyMap with an std::map member variable declared in it, and try to implement CMap similar functions in your CMyMap. However, you cannot simulate hash code related functions of CMap via a std::map..
Did I understand your problem correctly?
--
Arman
|
|
|
|
|
Hi All,
How to get the available ports for serial port communcation.
Thanks & Regards,
Anitha
|
|
|
|
|
You can use CP article Search engine..
See here[^]. I hope it helps.
Regards,
Sandip.
|
|
|
|
|
Check out the Win32_SerialPortConfiguration and Win32_SerialPort WMI classes.
"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
|
|
|
|
|
Hi all,
I am just curious to know if there is a way to find the HWND of a window, given no actual window title and no definitive process name. Although I could get a handle by using the process name, I'd rather not since users might rename the executable file to something else.
I am attempting to prevent two instances of one app from being run at once, so I stuck a mutex in. I want my app to send a message to the already running program and close. However, my app needs the HWND of the other running app to send a message to it with SendMessage. The problem is, my app does not have an actual "window", meaning that I can't get it's HWND with FindWindow. It's derived from CFrameWnd and doesn't show up in taskmgr (FindWindow).
Any suggestions on how to accomplish this? Thanks in advance 
|
|
|
|
|
How about saving the HWND into a registry location?
«_Superman_»
|
|
|
|
|
That'd actually be a good idea.
I'll try that. But is there any more...elegant..way to do this? 
|
|
|
|
|
What about using events..??
Regards,
Sandip.
|
|
|
|
|
Rather than a mutex (which I'm presuming has a unique name), you could have a uniquely named bit of shared memory, in which the first process to run could store things like the HWND to post a message to?
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
|
|
|
|
|
I'm probably going with this idea. Thanks a lot. 
|
|
|
|
|
Hi,
I was wondering what is the order of API calls to replace a peice of text in a Rich Edit Control Dialog
I do the following
WM_SETSEXT to send the Text the Rich Edit Dialog BOX
The EM_SETSEL 0,7 setting the selection for char 0 - 7
Then doing the SetCharFormat to set the Character fromat to red
memset( &cf, 0, sizeof cf );
cf.cbSize = sizeof cf;
cf.dwMask = CFM_COLOR;
cf.crTextColor = RGB(255,0,0);
SendMessage(RichWindow,EM_SETCHARFORMAT,SCF_SELECTION,(LPARAM) &cf);
Then the replacement text
strncpy(addr,"00000000",8);
SendMessage(RichWindow,EM_REPLACESEL,TRUE,(LPARAM) addr);
However more then 8 charcters are replaced seeems like 9 or 10
|
|
|
|
|
I was wondering what people reckon a good way of logging in C++ would be?
Coming from a java background, I very much like log4j's system:
- it handles file output (and sizing) automatically
- very configurable
- easy to install and use in eclipse
Now, I've come across two loggers for C++ which seem
to be the C++ version of log4j: log4cxx (by apache) and log4cpp (by someone else: http://log4cpp.sourceforge.net/[^] )
OK, so first attempt at getting log4cxx working in Eclipse (running on kubuntu) was not fruitful:
The apache website, nor anywwhere else has much info on getting log4cxx up and running in eclipse.
(after installing log4cxx via "sudo aptitude install liblog4cxx9c2a" and including the header files in my c++ project in eclipse, it says it cant find the header files... i've searched and cant find them either !)
I would so love to use log4cxx since it was built by Apache and probably works really well but I really dont want to waste hours
again trying to get it to work in Eclipse (or anywwhere else for that matter). Same with log4cpp
IF anyone knows of a good logging library / class which handles (log)file creation automatically and is
easily used within eclipse, it would be much appreciated !!!!
gvanto
c++ logging newbie
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
