I have a QString
in my sources.
So I need to convert it to integer without \"Kb\".
I tried Abcd.toInt()
but it does not work
Don't forget to check if the conversion was successful!
bool ok;
auto str= tr("1337");
str.toDouble(&ok); // returns 1337.0, ok set to true
auto strr= tr("LEET");
strr.toDouble(&ok); // returns 0.0, ok set to false
On the comments:
sscanf(Abcd, "%f %s", &f,&s);
Gives an Error.
This is the right way:
sscanf(Abcd, "%f %s", &f,qPrintable(s));
You don't have all digit characters in your string. So you have to split by space
QString Abcd = "123.5 Kb";
Abcd.split(" ")[0].toInt(); //convert the first part to Int
Abcd.split(" ")[0].toDouble(); //convert the first part to double
Abcd.split(" ")[0].toFloat(); //convert the first part to float
Update: I am updating an old answer. That was a straight forward answer to the specific question, with a strict assumption. However as noted by @DomTomCat in comments and @Mikhail in answer, In general one should always check whether the operation is successful or not. So using a boolean flag is necessary.
bool flag;
double v = Abcd.split(" ")[0].toDouble(&flag);
if(flag){
// use v
}
Also if you are taking that string as user input, then you should also be doubtful about whether the string is really splitable with space. If there is a possibility that the assumption may break then a regex verifier is more preferable. A regex like the following will extract the floating point value and the prefix character of 'b'. Then you can safely convert the captured strings to double.
([0-9]*\.?[0-9]+)\s+(\w[bB])
You can have an utility function like the following
QPair<double, QString> split_size_str(const QString& str){
QRegExp regex("([0-9]*\\.?[0-9]+)\\s+(\\w[bB])");
int pos = regex.indexIn(str);
QStringList captures = regex.capturedTexts();
if(captures.count() > 1){
double value = captures[1].toDouble(); // should succeed as regex matched
QString unit = captures[2]; // should succeed as regex matched
return qMakePair(value, unit);
}
return qMakePair(0.0f, QString());
}
Use .toInt()
for int .toFloat()
for float and .toDouble()
for double
toInt();
The string you have here contains a floating point number with a unit. I'd recommend splitting that string into a number and unit part with QString::split()
.
Then use toDouble()
to get a floating point number and round as you want.
You can use:
QString str = "10";
int n = str.toInt();
Output:
n = 10