Some example usage of apex:param

 Here are some example usage of the apex:param tag in visualforce page :

<apex:outputText value="{0,date,dd/MM/yyyy}">
        <apex:param value="{!E.Date_du_collecte__c}"/>
    </apex:outputText>
    //convert a decimal to integer in VF
    <apex:outputText value="{0,number,integer}">
        <apex:param value="{!d.key.Degustateur__r.PonderationNiveauTechnique__pc}"/>
    </apex:outputText>
    //replace . by ,
    <apex:outputText value="{0}">
        <apex:param value="{!SUBSTITUTE(TEXT(r.header.InvoiceAmount__c), '.', ',' )}"/>
    </apex:outputText>

    <apex:commandButton value="Process Nickname" action="{!processButtonClick}">
       <apex:param name="nickName" value="{!contact.firstname}" assignTo="{!nickName}"/>
    </apex:commandButton>
   
    <apex:commandButton action="{!DisplayAcompteJournal}" rendered="{!show.showSaveLines}" rerender="head02" value="Afficher Acompte">
        <apex:param name="pos" value="{!numCompteGeneralLine}" assignTo="{!linePosition}" />
    </apex:commandButton>