Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • World
  • Users
  • Groups
Skins
  • Light
  • Cerulean
  • Cosmo
  • Flatly
  • Journal
  • Litera
  • Lumen
  • Lux
  • Materia
  • Minty
  • Morph
  • Pulse
  • Sandstone
  • Simplex
  • Sketchy
  • Spacelab
  • United
  • Yeti
  • Zephyr
  • Dark
  • Cyborg
  • Darkly
  • Quartz
  • Slate
  • Solar
  • Superhero
  • Vapor

  • Default (No Skin)
  • No Skin
Collapse
Code Project
  1. Home
  2. General Programming
  3. C / C++ / MFC
  4. A Simple C++ Question.

A Simple C++ Question.

Scheduled Pinned Locked Moved C / C++ / MFC
questionc++comhelp
14 Posts 7 Posters 0 Views 1 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • S Sivaraman Dhamodharan

    Have a look at the below code:

    #include "stdafx.h"
    #include "conio.h"

    int _tmain(int argc, _TCHAR* argv[])
    {
    //Snippet 1
    char name[20] = "Some Name";
    printf("%s\n", name);
    name[1] = 'a';
    printf("%s\n", name);

    //Snippet 2
    char \* name2 = "Some Name";
    printf("%s\\n", name2);
    name2\[1\] = 'a';
    printf("%s\\n", name2);
    
    getch();
    return 0;
    

    }

    Why we get Runtime error when we modify name2[1] = 'a';?

    Programming Article

    M Offline
    M Offline
    Maximilien
    wrote on last edited by
    #4

    You are trying to modify a const char array (pointer). This is not C++. if you were writing proper C++, you would not get those problems (or a lot less likely).

    std::string name = "some name";
    std::cout << name << std::endl;

    std::string name2 = "some name";
    std::cout << name2 << std::endl;

    name2[1] = 'a'; // need to check that the index is within the string size.
    std::cout << name2 << std::endl;

    Watched code never compiles.

    C A 2 Replies Last reply
    0
    • M Maximilien

      You are trying to modify a const char array (pointer). This is not C++. if you were writing proper C++, you would not get those problems (or a lot less likely).

      std::string name = "some name";
      std::cout << name << std::endl;

      std::string name2 = "some name";
      std::cout << name2 << std::endl;

      name2[1] = 'a'; // need to check that the index is within the string size.
      std::cout << name2 << std::endl;

      Watched code never compiles.

      C Offline
      C Offline
      Chuck OToole
      wrote on last edited by
      #5

      Technically, to pick nits, it *is* C++ as C++ is a superset of C. What you are really saying is that it isn't "Object Oriented Programming" which is true, but it is still within the definition of C++.

      J A 2 Replies Last reply
      0
      • M Maximilien

        You are trying to modify a const char array (pointer). This is not C++. if you were writing proper C++, you would not get those problems (or a lot less likely).

        std::string name = "some name";
        std::cout << name << std::endl;

        std::string name2 = "some name";
        std::cout << name2 << std::endl;

        name2[1] = 'a'; // need to check that the index is within the string size.
        std::cout << name2 << std::endl;

        Watched code never compiles.

        A Offline
        A Offline
        Albert Holguin
        wrote on last edited by
        #6

        Agree with Chuck... technically it is C++.

        1 Reply Last reply
        0
        • C Chuck OToole

          Technically, to pick nits, it *is* C++ as C++ is a superset of C. What you are really saying is that it isn't "Object Oriented Programming" which is true, but it is still within the definition of C++.

          J Offline
          J Offline
          jschell
          wrote on last edited by
          #7

          Chuck O'Toole wrote:

          Technically, to pick nits, it *is* C++ as C++ is a superset of C

          Does the newest ANSI C++ standard incorporate the latest ANSI C standard as a subset? Last I heard that was not the case

          C 1 Reply Last reply
          0
          • C Chuck OToole

            Technically, to pick nits, it *is* C++ as C++ is a superset of C. What you are really saying is that it isn't "Object Oriented Programming" which is true, but it is still within the definition of C++.

            A Offline
            A Offline
            Aescleal
            wrote on last edited by
            #8

            C++98 is not a superset of C90 - especially when you consider const and what happens when you cast away const. C allows modification of literals (string and constants) through pointers while C++ doesn't or rather considers it undefined behaviour.

            C 1 Reply Last reply
            0
            • J jschell

              Chuck O'Toole wrote:

              Technically, to pick nits, it *is* C++ as C++ is a superset of C

              Does the newest ANSI C++ standard incorporate the latest ANSI C standard as a subset? Last I heard that was not the case

              C Offline
              C Offline
              Chuck OToole
              wrote on last edited by
              #9

              The point is, C++ did *not* decommit the "char" data type nor pointers. std::string is *not* the only way to do string manipulation in C++. It may be the perferred way for some people but it's not the only way.

              J 1 Reply Last reply
              0
              • A Aescleal

                C++98 is not a superset of C90 - especially when you consider const and what happens when you cast away const. C allows modification of literals (string and constants) through pointers while C++ doesn't or rather considers it undefined behaviour.

                C Offline
                C Offline
                Chuck OToole
                wrote on last edited by
                #10

                The point is, C++ did *not* decommit the "char" data type nor pointers. std::string is *not* the only way to do string manipulation in C++. It may be the perferred way for some people but it's not the only way.

                1 Reply Last reply
                0
                • C Chuck OToole

                  The point is, C++ did *not* decommit the "char" data type nor pointers. std::string is *not* the only way to do string manipulation in C++. It may be the perferred way for some people but it's not the only way.

                  J Offline
                  J Offline
                  jschell
                  wrote on last edited by
                  #11

                  Chuck O'Toole wrote:

                  The point is, C++ did *not* decommit the "char" data type nor pointer

                  I was responding to what appeared to be a general comment about the language in general and in its entirety and not just one small part. And that general comment, at this time (new standards), is wrong.

                  C 1 Reply Last reply
                  0
                  • J jschell

                    Chuck O'Toole wrote:

                    The point is, C++ did *not* decommit the "char" data type nor pointer

                    I was responding to what appeared to be a general comment about the language in general and in its entirety and not just one small part. And that general comment, at this time (new standards), is wrong.

                    C Offline
                    C Offline
                    Chuck OToole
                    wrote on last edited by
                    #12

                    Context dude, gotta read comments in the context of the thread

                    J 1 Reply Last reply
                    0
                    • C Chuck OToole

                      Context dude, gotta read comments in the context of the thread

                      J Offline
                      J Offline
                      jschell
                      wrote on last edited by
                      #13

                      Chuck O'Toole wrote:

                      Context dude, gotta read comments in the context of the thread

                      And respond in that context. Since another poster read your response in way similar to the way I read it, it suggests that your response is the one at fault.

                      1 Reply Last reply
                      0
                      • D David Crow

                        It all boils down to the difference between an array and a pointer. For name, you have set aside room for 20 characters (that are initialized to "Some Name"). For name2, you are pointing to a static piece of memory. That memory cannot be changed.

                        "One man's wage rise is another man's price increase." - Harold Wilson

                        "Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

                        "Show me a community that obeys the Ten Commandments and I'll show you a less crowded prison system." - Anonymous

                        S Offline
                        S Offline
                        Sivaraman Dhamodharan
                        wrote on last edited by
                        #14

                        Thanks Crow. That is constant piece of memory.

                        Programming Article

                        1 Reply Last reply
                        0
                        Reply
                        • Reply as topic
                        Log in to reply
                        • Oldest to Newest
                        • Newest to Oldest
                        • Most Votes


                        • Login

                        • Don't have an account? Register

                        • Login or register to search.
                        • First post
                          Last post
                        0
                        • Categories
                        • Recent
                        • Tags
                        • Popular
                        • World
                        • Users
                        • Groups