[b]myprocess.cpp[/b]

#include "myprocess.h"

myProcess::myProcess(QWidget *parent) : QDialog(parent)
{
    sb.setText("Start SBCL");
    ib.setText("Input Command");
    lb.setText("(+ 3 2)");
    QVBoxLayout *vl=new QVBoxLayout;
    vl->addWidget(&sb);
    vl->addWidget(&te);
    vl->addWidget(&le);
    vl->addWidget(&ib);
    vl->addWidget(&lb);
    setLayout(vl);

    connect(&sb,SIGNAL(clicked()),this,SLOT(startProcess()));
    connect(&ib,SIGNAL(clicked()),this,SLOT(doInput()));
    connect(&lb,SIGNAL(clicked()),this,SLOT(mathstart()));
    connect(&myProc,SIGNAL(readyReadStandardOutput()),this,SLOT(showOutput()));
    connect(&myProc,SIGNAL(readyReadStandardError()),this,SLOT(showOutput()));
}

void myProcess::startProcess()
{
    QString prog="sbcl";
    myProc.start(prog);
    if(myProc.waitForStarted())
        te.append(QString("Program <b>%1</b> started").arg(prog));
    else
        te.append(QString("Can't start program <b>%1</b>").arg(prog));
}

void myProcess::doInput()
{
    QString s=le.text()+"\n";
    if(myProc.write(s.toAscii())!=-1) le.clear();
}

void myProcess::showOutput()
{
    te.append(QString::fromLocal8Bit(myProc.readAllStandardOutput()));
    te.append(QString::fromLocal8Bit(myProc.readAllStandardError()));
}
void myProcess::mathstart()
{
    QString h="(+ 3 2)\n";
    myProc.write(h.toAscii());
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    myProcess p;
    p.show();
    return a.exec();
}

[b]myprocess.h[/b]

#include <QtGui>

class myProcess : public QDialog
{
    Q_OBJECT

public:
    myProcess(QWidget *parent=0);
private slots:
    void startProcess();
    void showOutput();
    void doInput();
    void mathstart();
private:
    QProcess myProc;
    QTextEdit te;
    QLineEdit le;
    QPushButton sb,ib,lb;

};