When developing software to Qt had a chance encounter with one nuance when outputting floating point numbers through qDebug() . The problem is that not all characters are displayed after the decimal point. In the same sins and output std::cout .

This user case may occur in the following situation:

You have a QString object that contains a certain number of "8564.26495574", which we translate into a floating point number using toDouble() method, and check the result with the output qDebug (), but that's bad luck, the output is false.

QString str("8564.26495574");
qDebug() << str.toDouble();

// The output is -> 8564.26

But in fact we have absolutely the right number, that is, from a string was received number 8564.26495574 just concluded qDebug() shows the rounded result.

The same can be observed if you try to bring a double number value to qDebug() .

double a = 8564.26495574;
qDebug() << a;

// The output is -> 8564.26