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问题 I am following a MERN stack tutorial in which a parent component Dashboard passes an array of objects from its own props (after mapStateToProps) to another component Education. Trying to iterate through this array in Education component gives me the above mentioned error. Please help, the tutorial seemed to have no errors and I have followed it perfectly so why the issue? <Education education={profile.education}/> (passing the prop in Dashboard.js) education is an array of objects inside an

问题 I got a photo competition that seems to work fine but when I upload a photo I get a blank screen. I checked the error log and found this: PHP Fatal error: Call to undefined function exif_imagetype() in /home/fbtabvhk/public_html/pinkdrive_selfie/contest/libs/upload/save.php on line 27 This is the code on line 27: if (exif_imagetype($_FILES['files']['tmp_name'][0]) === FALSE) 回答1: You have to have the exif extension compiled and enabled for this function to work. This extension has good

问题 I'm trying to pass value from one component to another. First one looks like this: class ListStation extends Component { constructor(props) { super(props) this.state = { stations: [] } this.editStation = this.editStation.bind(this); } editStation(id) { this.props.history.push(`/add-station/${id}`); } componentDidMount() { StationService.getStations().then((res) => { this.setState({ stations: res.data }); }) } } render() { return ( <div> <tbody> {this.state.stations.map( station => <tr key=

问题 I get an error when I include a header file, but not if I include the source file instead. The function is defined in the source file like this: /* in User.c */ struct User { const char* name; }; struct User* addedUser(const char* name) { struct User* user = malloc(sizeof(struct User)); user->name = name; return user; } And used like this: /* in main.c */ int test_addedUser() { char* newName = "Fooface"; struct User* newUser = addedUser(newName); assert(!strcmp(newName, newUser->name));

问题 This works (plots an "empty" figure): function testme plot(1) This works (returns 1): function testme plot = @(x)x; plot(1) This does not (Error: "Undefined function or variable 'plot'."): function testme if 0 plot = @(x)x; end plot(1) What's going on here? Why does rewriting but not redefining an already defined function render the function undefined? Note 1: this is not specific for builtin functions; the following code returns the same error: function testme if 0 myfun = @(x)x; end myfun(1

问题 This works (plots an "empty" figure): function testme plot(1) This works (returns 1): function testme plot = @(x)x; plot(1) This does not (Error: "Undefined function or variable 'plot'."): function testme if 0 plot = @(x)x; end plot(1) What's going on here? Why does rewriting but not redefining an already defined function render the function undefined? Note 1: this is not specific for builtin functions; the following code returns the same error: function testme if 0 myfun = @(x)x; end myfun(1

问题 I'm trying to create blade directive which echo variable (if variable defined) or echo "no data" if variable undefined. This is my code in AppServiceProvider.php : <?php namespace App\Providers; use Blade; use Illuminate\Support\ServiceProvider; class AppServiceProvider extends ServiceProvider { /** * Bootstrap any application services. * * @return void */ public function boot() { Blade::directive('p', function($ex) { error_log(print_r($ex,true)); return '<?php $defined_vars = get_defined

问题 I'm trying to create blade directive which echo variable (if variable defined) or echo "no data" if variable undefined. This is my code in AppServiceProvider.php : <?php namespace App\Providers; use Blade; use Illuminate\Support\ServiceProvider; class AppServiceProvider extends ServiceProvider { /** * Bootstrap any application services. * * @return void */ public function boot() { Blade::directive('p', function($ex) { error_log(print_r($ex,true)); return '<?php $defined_vars = get_defined

问题 I'm trying to create blade directive which echo variable (if variable defined) or echo "no data" if variable undefined. This is my code in AppServiceProvider.php : <?php namespace App\Providers; use Blade; use Illuminate\Support\ServiceProvider; class AppServiceProvider extends ServiceProvider { /** * Bootstrap any application services. * * @return void */ public function boot() { Blade::directive('p', function($ex) { error_log(print_r($ex,true)); return '<?php $defined_vars = get_defined

问题 So I am having trouble creating a function that will filter and sort dates and its data to be placed in an array of objects. The issue I am having is a different but similar scenario. The original question was taken from here: Filtering undefined from array of objects in Javascript Lets say that var arrObject has more than 2 items in an array. See code below.I want to filter any empty string or undefined values and with any items in the array and sort then asc. order by dates. In the new