Is there a "new" style for casting?

[saber]

i am getting lot of this warning in my code

any fixes?

[J.Hilk]

@saber
take a look at the c++ basic's

http://www.cplusplus.com/doc/tutorial/typecasting/

the tl;dr version

double x = 10.3;
int y;
y = int (x); // functional notation
y = (int) x; // c-like cast notation

c++ casting

dynamic_cast <new_type> (expression)
reinterpret_cast <new_type> (expression)
static_cast <new_type> (expression)
const_cast <new_type> (expression)

[aha_1980]

@J.Hilk said in Is there a "new" style for casting?:

y = int (x); // functional notation

Note that this is also a valid C++ style cast, which is still used for numeric types, as it's less noise than the xxx_cast<>() versions.

[J.Hilk]

@aha_1980
thanks; I Didn't make that clear enough, my bad for simply copy and pasting :-)

[saber]

can you modify those warnings lines in "new cast"
it will make it clear for me.
thanks.
@jsulm can you ? please

// Check available space on destination before we start
    struct statfs info;
    statfs(newPath.toLocal8Bit(), &info);
    if ((qint64) info.f_bavail * info.f_bsize < total) {  // here 

      // If it is a cut/move on the same device it doesn't matter
      if (cutList.count()) {
        qint64 driveSize = (qint64) info.f_bavail*info.f_bsize;  // here 
        statfs(files.at(0).path().toLocal8Bit(),&info);

        // Same device?
        if ((qint64) info.f_bavail*info.f_bsize != driveSize) {  // here 
          emit copyProgressFinished(2, newFiles);
          return 0;
        }
      } else {
        emit copyProgressFinished(2, newFiles);
        return 0;
      }
    }

[J.Hilk]

@saber
Don't post screenshots of your code, makes it difficult to actuallly quote it and modify it.

[jsulm]

@saber said in Is there a "new" style for casting?:

can you ? please

I already did in one of your other threads

[saber]

@J.Hilk i did others

if (cutList.count()) {
        qint64 driveSize = static_cast<qint64>(info.f_bavail) * (info.f_bsize) ;
        statfs(files.at(0).path().toLocal8Bit(),&info);

        // Same device?
        if (static_cast<qint64>(info.f_bavail) * (info.f_bsize)  != driveSize) {
          emit copyProgressFinished(2, newFiles);
          return 0;
        }

[saber]

@J.Hilk i got other warnings like

    int x = screensize().width()  * .8;
    int y = screensize().height() * .7;

and warning is

/home/shaber/Desktop/Folder/work3/coreApps/app/corefm/corefm.cpp:29: warning: implicit conversion turns floating-point number into integer: 'double' to 'int'

[jsulm]

@saber You are multiplying an int with a double and assign the result to an int, this is dangerous.
To get rid of the warning you can cast the result of the multiplication to int or (even better) think about what you're doing and whether rounding in a defined way would be better.

[J.Hilk]

@saber said in Is there a "new" style for casting?:

@J.Hilk i got other warnings like

    int x = screensize().width()  * .8;
    int y = screensize().height() * .7;

and warning is

/home/shaber/Desktop/Folder/work3/coreApps/app/corefm/corefm.cpp:29: warning: implicit conversion turns floating-point number into integer: 'double' to 'int'

of course,
this breaks down to

int = int * double;
int = double <- precision loss, truncated after the decimal point

this is an implicit conversion of double to int, therefore cast it alsoif thats intendet behaviour:

int x = static_cast<int>(screensize().width()  * .8);

or round it

int x = qRound(screensize().width()  * .8);

[Abrar]

@saber as @J-Hilk and @jsulm said
int x = int(screensize().width() * .8);
int y = int(screensize().height() * .7);

@J-Hilk and @jsulm make it very easy to me to understand.

[jsulm]

@Abrar said in Is there a "new" style for casting?:

int x = int(screensize().width() * .8);
int y = int(screensize().height() * .7);

This would bring back the warning about old style cast.

[Abrar]

@jsulm is it look like this
int x = static_cast<int>(screensize().width() * .8);
int y = static_cast<int>(screensize().height() * .7);

If not tell me the difference between new cast and old...plz

[jsulm]

@Abrar said in Is there a "new" style for casting?:

static_cast<int>(screensize().width() * .8)

Yes, this is C++ type cast.

(int)(someVariabl);

Old C style cast which should not be used in C++.
See https://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-const-cast-and-reinterpret-cast-be-used

[J.Hilk]

@jsulm
technically,

int(someVariabl);

is a valid "conversion", as it's a functional notation

[Abrar]

@jsulm ok now understand the difference.
Thanks...

[jsulm]

@J.Hilk Both are C-style casts

[saber]

guys what a
@saber = static_cast<learn>( @jsulm and @J-Hilk ; (i think)

thanks.learned alot.

[Abrar]

@saber you wrote the clever statement ever.
!!!!