CODEWITHSUNDEEP
c++qttype-conversionqstring
Thomas
Thomas

Reputation: 1706

How can I convert a QString of numbers to an array of int?

I have a QString containing a series of numbers for example

QString path = "11100332001 234 554 9394";

I want to iterate over the variable length string

for (int i=0; i<path.length(); i++){

}

and be able to acces each number as an int individually.

I haven't been able to do so however. Question: How can I convert a QString of numbers to an array of int?

I know I can convert the QString to an int using path.toInt() but that doesn't help me.

When trying to convert it to a char first I get an error: cannot convert 'const QChar to char'.

for (int i=0; i<path.length(); i++){
        char c = path.at(i);
        int j = atoi(&c);
        //player->movePlayer(direction);
    }

Upvotes: 6

Views: 14704

Answers (4)

Stephen B
Stephen B

Reputation: 93

I have used the answer by Antoyo myself but I ran into an issue today. digitValue() is not the same as comparing a char in C using atoi like the op Thomas was trying to do. So while Thomas was trying to do this:

for (int i=0; i<path.length(); i++){
        char c = path.at(i);
        int j = atoi(&c);
        //player->movePlayer(direction);
    }

with digitValue() it would have become this:

for (int i=0; i<path.length(); i++){
        int j = path.at(i).digitValue();
        //player->movePlayer(direction);
    }

However this does not have the expected results if there are any letters in the string. For example in C, if the string has a mix of Letters and numbers then any char you use atoi on will return a 0 in place of a letter. digitValue() however does not return 0 for a letter. It may be a good idea to do a check for isDigit() first if you have any concerns about letters ending up in your string and the final result would look like this:

int j = 0;
for (int i=0; i<path.length(); i++){
        if (path.at(i).isDigit())
            j = path.at(i).digitValue();
        else
            j = 0;
        //player->movePlayer(direction);
    }

This may not have been a concern for the OP but since this is one of the top Google results for getting numbers from a string in QT it might help someone else, especially if you're trying to get a QT application to behave the same as some embedded C code on a device.

Upvotes: 1

Youssef Bouhjira
Youssef Bouhjira

Reputation: 1629

you can use split to obtain an array of substrings separated by the separator you want in this case it's a space , here is an example :

QString str("123 457 89");

QStringList list = str.split(" ",QString::SkipEmptyParts);

foreach(QString num, list)
    cout << num.toInt() << endl;

Upvotes: 10

sashoalm
sashoalm

Reputation: 79447

Use QTextStream:

QString str = "123 234   23123  432";
QTextStream stream(&str);
QList<int> array;
while (!stream.atEnd()) {
    int number;
    stream >> number;
    array.append(number);
}

Upvotes: 3

antoyo
antoyo

Reputation: 11913

You may get every character (QChar) with the [] operator and use the digitValue() method on them to get the integer.

Upvotes: 4

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