Hi Every one,

I wrote program using Extension concpt

Apex program
public class Quick_quote {
    public Account acc      {set;get;}
    public contact con      {set;get;}
    public opportunity opt  {set;get;}
    public string quotename {set;get;}
    
    public Quick_quote(Apexpages.StandardController controller){
        List<string> fields = new List<string>{'name','phone','industry','rating'};
            controller.addfields(fields);
           con=new contact();
           opt= new opportunity();
        acc=(account)controller.getRecord();
    } 
    }
Visual force program

<apex:page standardController="Account" extensions="Quick_quote">
   <apex:sectionHeader title="Quick quote" subtitle="new quick quote"/> 
    <apex:form>
        <apex:pageblock>
    <apex:pageBlockSection title="Account" collapsible="false">
        <apex:inputField value="{!Account.name}"/>
        <apex:inputField value="{!account.phone}"/>
        <apex:inputField value="{!account.industry}"/>
        <apex:inputField value="{!account.rating}"/>
        </apex:pageBlockSection>
        <apex:pageBlockSection title="Contact" collapsible="false">
            <apex:inputText value="{!con.firstname}"/>
            <apex:inputText value="{!con.lastname}"/>
            <apex:inputText value="{!con.phone}"/>
            <apex:inputText value="{!con.Email}"/>
        </apex:pageBlockSection>
            <apex:pageBlockSection title="opportunty" collapsible="false">
                <apex:inputText value="{!quotename}"/>
                </apex:pageBlockSection>
            </apex:pageblock>
    </apex:form>
    </apex:page>

When i am executig this program i am getting error 
Error-
Maximum stack depth reached: 1001 

Thank you
surender reddy