nlohmann json has a string member called name, how can I check it is null or valid string





.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ height:90px;width:728px;box-sizing:border-box;
}







1















I know that I have this:



json var["thirdName"].get<std::string>().c_str();


It is used in C++. The protocol says this member is mandatory, but lots of people don't have third name.



I got exception if it is



nullptr;


, because I can say



var["thirdName"] = nullptr;


How can I easily check if it is valid or not?



I've found only one very complex form.






linux c++14 nullptr nlohmann-json







share|improve this question





























    1















    I know that I have this:



    json var["thirdName"].get<std::string>().c_str();


    It is used in C++. The protocol says this member is mandatory, but lots of people don't have third name.



    I got exception if it is



    nullptr;


    , because I can say



    var["thirdName"] = nullptr;


    How can I easily check if it is valid or not?



    I've found only one very complex form.






    linux c++14 nullptr nlohmann-json







    share|improve this question

























      1












      1








      1








      I know that I have this:



      json var["thirdName"].get<std::string>().c_str();


      It is used in C++. The protocol says this member is mandatory, but lots of people don't have third name.



      I got exception if it is



      nullptr;


      , because I can say



      var["thirdName"] = nullptr;


      How can I easily check if it is valid or not?



      I've found only one very complex form.






      linux c++14 nullptr nlohmann-json







      share|improve this question














      I know that I have this:



      json var["thirdName"].get<std::string>().c_str();


      It is used in C++. The protocol says this member is mandatory, but lots of people don't have third name.



      I got exception if it is



      nullptr;


      , because I can say



      var["thirdName"] = nullptr;


      How can I easily check if it is valid or not?



      I've found only one very complex form.






      linux c++14 nullptr nlohmann-json




      linux c++14 nullptr nlohmann-json






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Jan 3 at 12:52









      TamasTamas

      123




      123
























          1 Answer
          1






          active

          oldest

          votes


















          1














          You can use the count method:



          if (var.count("thirdName") > 0) {
          
  ...
          
}


          Personally, I would omit the > 0:



          if (var.count("thirdName")) {
          
  ...
          
}





          share|improve this answer
























            Your Answer






            StackExchange.ifUsing("editor", function () {
            StackExchange.using("externalEditor", function () {
            StackExchange.using("snippets", function () {
            StackExchange.snippets.init();
            });
            });
            }, "code-snippets");

            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "1"
            };
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function() {
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled) {
            StackExchange.using("snippets", function() {
            createEditor();
            });
            }
            else {
            createEditor();
            }
            });

            function createEditor() {
            StackExchange.prepareEditor({
            heartbeatType: 'answer',
            autoActivateHeartbeat: false,
            convertImagesToLinks: true,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            bindNavPrevention: true,
            postfix: "",
            imageUploader: {
            brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
            contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
            allowUrls: true
            },
            onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            });


            }
            });














            draft saved

            draft discarded


















            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f54022703%2fnlohmann-json-has-a-string-member-called-name-how-can-i-check-it-is-null-or-val%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1














            You can use the count method:



            if (var.count("thirdName") > 0) {
            
  ...
            
}


            Personally, I would omit the > 0:



            if (var.count("thirdName")) {
            
  ...
            
}





            share|improve this answer




























              1














              You can use the count method:



              if (var.count("thirdName") > 0) {
              
  ...
              
}


              Personally, I would omit the > 0:



              if (var.count("thirdName")) {
              
  ...
              
}





              share|improve this answer


























                1












                1








                1







                You can use the count method:



                if (var.count("thirdName") > 0) {
                
  ...
                
}


                Personally, I would omit the > 0:



                if (var.count("thirdName")) {
                
  ...
                
}





                share|improve this answer













                You can use the count method:



                if (var.count("thirdName") > 0) {
                
  ...
                
}


                Personally, I would omit the > 0:



                if (var.count("thirdName")) {
                
  ...
                
}






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Jan 3 at 12:55









                mrksmrks

                4,7401938




                4,7401938
































                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Stack Overflow!


                    • Please be sure to answer the question. Provide details and share your research!

                    But avoid …



                    • Asking for help, clarification, or responding to other answers.

                    • Making statements based on opinion; back them up with references or personal experience.


                    To learn more, see our tips on writing great answers.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f54022703%2fnlohmann-json-has-a-string-member-called-name-how-can-i-check-it-is-null-or-val%23new-answer', 'question_page');
                    }
                    );

                    Post as a guest















                    Required, but never shown





















































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown

































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown







                    Popular posts from this blog

                    android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

                    Image
                    .everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ height:90px;width:728px;box-sizing:border-box; } 0 This is a simple project showing cubes on Unity, exported to android project and imported on Android studio. On maifest file it showed following warning: Expecting <uses-feature android:name="android.software.leanback" android:required="false" /> tag I have no information about it. And also on default emptyview android project does not use/mention this feature. I know it is required by TV's and such but why its not added by default? Why is this? And Should I concern about it? android unity3d
                    Read more

                    SQL update select statement

                    Image
                    0 I'm trying to update an entry in my database (postgresql). I'm having a problem with updating the query: INSERT INTO prices (price, product_id) SELECT product_price, commn_id FROM products_temp as prod WHERE NOT EXISTS (SELECT * FROM prices od WHERE prod.commn_id = od.product_id) OR prod.product_price != ( SELECT price FROM prices as p WHERE p.product_id = prod.commn_id order by p.end desc LIMIT 1 ) Query works fine when i delete: OR prod.product_price != ( SELECT price FROM prices as p WHERE p.product_id = prod.commn_id order by p.end desc LIMIT 1 ) So it seems to me that it's looping through this operation. My question is, how can I fix it? sql postgresql
                    Read more

                    WPF add header to Image with URL pettitions [duplicate]

                    Image
                    up vote 0 down vote favorite This question already has an answer here: Image source URI requiring authorization 3 answers Add header to all* HTTP requests on a machine 1 answer first of all sorry for my english. Recently I added some security in the backend of my project, and now I need to send a validation code(apiKey) inside the headers to retrieve the images. I have a problem with ALL images in my project that I had attached in my UI. For example, before I had: <Image Height="90" Source="{Binding Video.Thumbnail}"/> Now I need to change my code to create a CUSTOM petition add the apiKey in the header:
                    Read more