CHeck if tbox Value is numeric

[Swankee]

If a user inputs a string into a textbox I'd like to check to see if the value was numeric or throw an error that the value was non numeric. So far I don't have anything aside from the error message. Thanks for your help

QString isNumber = "";
//grab value from lineEdit tb
    isNumber = m_ui->lineEdit->text();
 
//is it a + / - ?
if (isNumber == "+" || "-")
    {
        //Warning message
        m_ui->messageLbl->setText(m_ui->lineEdit->text() + " Is Not Valid. \n  Enter a Numeric Value");
    }

QString isNumber = "";
//grab value from lineEdit tb
    isNumber = m_ui->lineEdit->text();

//is it a + / - ?
if (isNumber == "+" || "-")
    {
        //Warning message
        m_ui->messageLbl->setText(m_ui->lineEdit->text() + " Is Not Valid. \n  Enter a Numeric Value");
    }

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[RSX]

QString str = m_ui->lineEdit->text();
foreach (QChar c, str) {
    if (c.isNumber()) {
         // one of the characters in string is a digit
    }
}

QString str = m_ui->lineEdit->text();
foreach (QChar c, str) {
    if (c.isNumber()) {
         // one of the characters in string is a digit
    }
}

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And this doesn't have sense. It will be always true as you are checking if "-" is non zero value, and in ASCII it's not.

if (isNumber == "+" || "-")

if (isNumber == "+" || "-")

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You can also use QValidator which will let user enter only specified characters into text box.

[Swankee]

QString str = m_ui->lineEdit->text();
foreach (QChar c, str) {
    if (c.isNumber()) {
         // one of the characters in string is a digit
    }
}

QString str = m_ui->lineEdit->text();
foreach (QChar c, str) {
    if (c.isNumber()) {
         // one of the characters in string is a digit
    }
}

To copy to clipboard, switch view to plain text mode 

And this doesn't have sense. It will be always true as you are checking if "-" is non zero value, and in ASCII it's not.

if (isNumber == "+" || "-")

if (isNumber == "+" || "-")

To copy to clipboard, switch view to plain text mode 

You can also use QValidator which will let user enter only specified characters into text box.

Cool thank you that worked. I'm going to be working more with validation in the coming days. I'll check out QValidator in the morning. Thanks much! Swank