problem in calling string function

[ramin.lich]

Hi,
here is my code

string cmdCommand(const string &command){
    fstream file("temp.txt");
    file.close();
    string cmd=command+ "> temp.txt";
    file.open("temp.txt");
    stringstream buffer;
    buffer << file.rdbuf();
    file.close();
    return buffer.str();
 
    try{
        result= cmdCommand("ping google.com");
    }
    catch(const char* exc)
    {
        cout<<exc;
    }
 
}
 
void MainWindow::on_pushButton_clicked()
{
    cmdCommand();
    ui->textBrowser->setText(QString::fromStdString(result));
}

string cmdCommand(const string &command){
    fstream file("temp.txt");
    file.close();
    string cmd=command+ "> temp.txt";
    file.open("temp.txt");
    stringstream buffer;
    buffer << file.rdbuf();
    file.close();
    return buffer.str();

    try{
        result= cmdCommand("ping google.com");
    }
    catch(const char* exc)
    {
        cout<<exc;
    }

}

void MainWindow::on_pushButton_clicked()
{
    cmdCommand();
    ui->textBrowser->setText(QString::fromStdString(result));
}

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when i compile this code this error shows:
error: too few arguments to function 'std::string cmdCommand(const string&)'
cmdCommand();
^
thanks