My Coding Reference

 sign in with Google Account in php , notes Error :    Warning: count(): Parameter must be an array or an object that implements Countable in C:\xampp\htdocs\coretechtive\vendor\guzzlehttp\guzzle\src\Handler\CurlFactory.php on line 67 Solution :  The problem is in PHP 7.2 the parameter for count() can't be NULL. The warning gets displayed when $this->handles equals NULL. Just replace line 67 in CurlFactory.php with the following: if (($this->handles ? count($this->handles) : 0) >= $this->maxHandles) { Error : Notice : Undefined index: expires_in in  C:\xampp\htdocs\coretechtive\vendor\google\apiclient\src\Google\Client.php  on line  470 Solution  :       $expired  = ( $created       + ( $this -> token [ 'expires_in' ] -  30 )) <  time (); replace above with  below : $expired  = ( $created ) <  time (); Error : ...

                                         HADOOP To Start and Stop Hadoop $ start-dfs.sh           --> To start hadoop $ start-yarn.sh         ---> To start yarn $ jps                         --> to view processes status $ stop-yarn.sh         --> To Stop yarn $ stop-dfs.sh           --> To stop hadoop To Copy File $ hadoop fs -mkdir vrush $ hadoop fs -ls $ hadoop fs -ls vrush $ ls -l $ hadoop fs -copyFromLocal data/*txt vrush MapReduce for Word Counting $ cd myc $  ls -l $  vi map.c $  press esc button :q  --> To escape from vi editor $  cc -o mymapper map.c $  cc -o myreduce reduce.c $  ls -l $  hado...

Redirect in React Router Redirect can use to redirect page to given path        when page doesn't exsist , it can be used instead of        showing 404 error page, so when user enter in wrong url        it will redirect to certain given path import   React   from   'react' import  { Route  ,  Switch ,  Redirect }  from   "react-router-dom" import   Contact   from   './RContact' import   About   from   './RAbout' import   ErrorMsg   from   './ErrorMsg' import   Navbar   from   './Navbar' import   User   from   './UseParams' import   Search   from   './RSearch' ; let   Service ...

useHistory in React Router import   React   from   'react' ; import  { useHistory }  from   'react-router-dom' ; let   User  = ()  => {         var   history  =  useHistory ();      return (          < >    <h1> user page </h1>     < button   onClick = { () => history . goBack () } > GO Back </ button >   < br />< br />< hr />     < button   onClick = { () => history . push ( '/' ) } > Hompage </ button >          </ >     ) } export   default   User ; useHistory gives the information about pages with visited , so that we can go back to previous  page using goBack()   function and can visit to any page we want using pu...

         useLocation in React Router import   React   from   'react' ; import  { useParams ,  useLocation }  from   'react-router-dom' ; let   User  = ()  => {      var  { fname ,  lname } =  useParams ();  // variable name must be same as you metion in route path                                      // we have to get it as object in {}        var   location  =  useLocation ();      // console.log(location);      return (          < >    ...

              useParams in React Router 1 st create Link user :  < NavLink    activeClassName = "active_class"   to = "/user" >  User  </ NavLink > 2nd metion link in route : < Switch >      { /* To Pass The Props to bellow about component */ }        < Route   exact   path = "/"   component = { () => < About   text = "About US"   /> } />        { /* We can also use render in place of component like bellow */ }        < Route   exact   path = "/contact"   render = { Contact } />          < Route   path = "/contact/service"   component = { Service } />     ...