if(this.state.username==''||this.state.username==undefined){
      had_error = true;
      this.setState({username_error:true});
    }else{
      had_error = false;
      this.setState({username_error:false});
    }
    if(!this.validateEmail(this.state.email)){
      had_error = true;
      this.setState({email_error:true});
    }else{
      had_error = false;
      this.setState({email_error:false});
    }
    if(this.state.password==''||this.state.password==undefined){
      had_error = true;
      this.setState({password_error:true});
    }else{
      had_error = false;
      this.setState({password_error:false});
    }