QRegExp rx((2[0-4]//d|25[0-5]|[01]?//d//d?)//.){3}(2[0-4]//d|25[0-4]|[01]?//d//d?);

ipLabel = new QLabel(tr("IP Address:"));
ipLineEdit = new QLineEdit;
ipLabel->setBuddy(ipLineEdit);

QValidator *validator = new QRegExpValidator(rx,this);
ipLineEdit->setValidator(validator);
ipLineEdit->setInputMask("000.000.000.000;");

实现框架下的验证输入的IP、子网掩码的合法性。（生成IP地址类）转自: http://www.qtcn.org/bbs/simple/?t18020.html

//ip.h
#include <qwidget.h>
#include <qstring.h>
#include <qlineedit.h>
#include <qvalidator.h>

#define IP_H

class IP : public QWidget
{
public:
IP ( const QString & text,QWidget *parent,const char *name );
QString getValue();
private:
QLineEdit * ip[4];
QIntValidator * ipv[4];
};

//ip.cpp
#include <qwidget.h>
#include <qlabel.h>
#include <qfont.h>
#include <qhBox.h>
#include <qlineedit.h>

#include "ip.h"

IP::IP(const QString & text,const char *nombre) : QWidget(parent,nombre,0)
{
QFont *fuente = new QFont("Arial",14,QFont::Normal);
fuente->setPixelSize(14);
QLabel *label = new QLabel( this );
label->setFont(* fuente);
label->setMinimumWidth(140);
label->setMaximumWidth(140);
QHBox * ipp = new QHBox((QWidget*) this);
ipp->setMinimumWidth(140);
ipp->setMaximumWidth(140);
for (int i=0; i<4; i++)
{
ip= new QLineEdit((QWidget*) ipp,nombre);
ip->setFont(* fuente);
ip->setMinimumWidth(30);
ip->setMaxLength(3);
ipv= new QIntValidator(0,255,(QObject*)ipp);
ip->setValidator(ipv);
}

label->move(0,0);
ipp->move(150,0);
label->setText(text);
// ip->setInputMask("000.000.000.000; ");
}

QString IP::getValue()
{
bool flag = false;
for (int i=0; i<4; i++)
if ( ip->text().isEmpty() )
flag = true;
if (flag)
return QString("0.0.0.0");
else
return QString(ip[0]->text()+ "." + ip[1]->text() + "." + ip[2]->text() + "." +
ip[3]->text());
}

设置具有IP输入格式的输入框模式。转自: http://www.qtcn.org/bbs/simple/?t28473.html

QRegExp rx("((2[0-4]//d|25[0-5]|[01]?//d//d?)//.){3}(2[0-4]//d|25[0-5]|[01]?//d//d?)"); QRegExpValidator v(rx,0); QLineEdit le; le.setValidator(&v); le.setInputMask("000.000.000.000;0");//只要加上;0保证有默认值即可使得正则和mask同时生效。