BIt Shift Error

[akshay123]

Hi all ,

i am developing an application where i need to shift the bit values .

quint64 bit_values;

int num=1;

bit_values = num<<42;

So the output of bit_values is 1024. This output is wrong .the correct output must be 4398046511104 . After analysing i came to know that . QT Compiler is of 32bit .

I tried to split 64bit values to two 32 bit values . but it failing . Please help me to resolve this issue

Thanks

[jsulm]

@akshay123 num is an int (32bit) that is the problem: you're shifting a 32bit int by 42 positions, this causes an overflow. Change num to quint64 and it will work.

Note: there is no such thing as "Qt compiler".

[akshay123]

Thanks @jsulm . As you have specifed i have changed it to uint64 . now tried to shift the values . but the result is same

[jsulm]

@akshay123 I tried and it works:

quint64 bit_values;
quint64 num = 1;
bit_values = num<<42;
qDebug() << bit_values;

Can you show your code?

[akshay123]

QList<quint64> temp_Shifted_values;
    quint64 tempValue=0;
    quint64 megaValue=0;
    for(int i=0; i< bit_Value.count(); i++)                  //bit values is a function parameter
    {
        tempValue = bit_Value.at(i) <<  bit_Low_Value.at(i);

        temp_Shifted_values.append(tempValue);
    }
    for(int i=0; i< temp_Shifted_values.count(); i++)
    {
        megaValue = megaValue | temp_Shifted_values.at(i);
    }

i am using ```
qt-opensource-windows-x86-mingw48_opengl-5.2.1

[jsulm]

@akshay123 What is the type of bit_Value ?

[akshay123]

the type of bit value is int

[jsulm]

@akshay123 So, you again do the same mistake: int is 32bit

[akshay123]

@jsulm Thanks . Sorry for the that . Since code size is very big . i didnt noticed . Thanks for your help