Question: I try to create a program that can evaluate simple math expression like "4+4". The expression is given from the user. 

The program saves it in a `char*` and then searches for binary operation (+,-,\*,:) and does the operation. 

The problem is that I can't figure out how to convert the **single** `char` into a `double` value. 

I know there is the `atof` function but I want to convert single `char`.

There is a way to do that without creating a `char*`?

Answer: 
I use that directive in one of my apps and I can get that button to appear by using the using the `file_browser_callback` function in the options. 

Do you get any errors in the JavaScript console? Perhaps you can make a simple CodePen or JS Fiddle of this so people can see your code?

EDIT: Here is a CodePen that does what you want ... it does get that button to appear. The `file_browser_callback` function just logs something to the browser's console but this shows that you can indeed have that button while using that Angular directive.

<http://codepen.io/michaelfromin/pen/BKOGZG>
YOUR HTML

```
<textarea data-ui-tinymce id="tinymce1" ng-model="data"></textarea>

<form id="image" style="width:0px;height:0;overflow:hidden">
    <input type="file" file-model="imageFile"/>
</form>

```

YOUR TINYMCE CONFIGURATION

```
tinymce.init({
    selector: 'textarea',

    automatic_uploads:true,
    file_browser_callback_types: 'file image media',
    file_browser_callback: function(field_name, url, type, win) {
        if(type=='image') {
            $('#editorImage input').click();
        }
    } 

});

```

YOUR DIRECTIVE

```
directive('fileModel', ['$parse', function ($parse) {
    return {
        restrict: 'A',
        link: function(scope, element, attrs) {
            var model = $parse(attrs.fileModel);
            var modelSetter = model.assign;

            element.bind('change', function(){
                scope.$apply(function(){
                    modelSetter(scope, element[0].files[0]);
                    scope.uploadImage();
                });
            });
        }
    };
}]);

```

YOUR CONTROLLER FUNCTION

```
$scope.uploadImage =function (){

    var fd = new FormData();
    fd.append('file', $scope.imageFile);
    $http({
        method:"POST",
        url: URL,
        data: fd,
        timeout:60000,
        transformRequest: angular.identity,
        headers: {'Content-Type': undefined}
    }).success(function(response,status){

    });

}

```