casting int to char

This is a discussion on casting int to char within the C++ Programming forums, part of the General Programming Boards category; i've been looking for this for a while, but unfortunatelly not too many descriptive insights..... well,.... correct me if i ...

  1. #1
    Registered User matheo917's Avatar
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    casting int to char

    i've been looking for this for a while, but unfortunatelly not too many descriptive insights.....

    well,.... correct me if i am wrong ......

    i need to cast from integer to character...

    i did............

    Code:
    int Selection;
    char Choice;
    Choice = (char) Selection;
    considering it is possible, so far so good... at least the compiler isn't complaining...

    the trick is, after converting that "int" to "char" i need to check whether that converted "Choice" is a numeric character......

    so i write:


    Code:
    #include <ctype.h>
    
    if(isdigit(Choice))
        cout << "is digit";

    .......all good
    after doing all of the above the compiler is all happy however the output is nowhere near... nothing works properly.....
    maybe i am doing this wrong ....



    any help would be appreciated
    Regards,
    mathe917

  2. #2
    Registered User blight2c's Avatar
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    i got this to compile, but i don't know if its what you want.

    Code:
    #include <iostream.h>
    #include <iomanip.h>
    
    #define tab '\t'
    
    main()
    {
    	int a=113;
    	char b;
    	b=static_cast<char>(a);
    	cout<<b;
    	return(0);
    }

  3. #3
    Registered User matheo917's Avatar
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    thanx for input.....
    however the casting is done fine...yours and mine.......

    the casting isn't the problem

    seams like the comparison isn't doing the job


    Regards,
    matheo917

  4. #4
    Used Registerer jdinger's Avatar
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    You're passing a char to isdigit. The param for isdigit is int.

    From MSDN:

    //
    int isdigit( int c );

    Parameter

    c

    Integer to test

    //

  5. #5
    Registered User blight2c's Avatar
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    i guess i don't understand what you mean by "numeric character" or what your trying to do with the comparison. i'd like to help. . .

  6. #6
    Code Goddess Prelude's Avatar
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    Does selection have an integer value such as 5, or a character value '5'? If it's the former then the test will fail unless you force a character conversion, not simply casting. This works peachy.
    Code:
    #include <iostream>
    #include <cctype>
    
    int main ( void )
    {
      int selection = 5;
      char choice = selection + '0';
      if ( isdigit ( choice ) )
        std::cout<< choice <<"\nThis works\n";
      return 0;
    }
    -Prelude
    My best code is written with the delete key.

  7. #7
    Registered User matheo917's Avatar
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    think of a simple do ... while loop ...
    which keeps looping around if the input is a number smaller than 0 or grater than 5, as well as if you would enter a letter "w" in place of an integer the program would crash, kind of loop forever, the reason why i needed that isdigit is to determine if the input is a letter "w" or a simple so called number value "4"......

    maybe i was using a wrong function???

    what you think??

    Regards,
    matheo917

  8. #8
    Registered User matheo917's Avatar
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    i played around with it from a different direction and still nothing...


    here's the code of this perticular loop:

    Code:
    int Selection;
      char Choice[2];
      do
       {
           cout << "1.  HELP MENU \n\n";
           cout << "2.  INVENTORY DIRECTORY \n\n";
           cout << "3.  DELIVERY INFORMATION \n\n";
           cout << "4.  ORDERING DIRECTORY \n\n";
           cout << "5.  WAITING LIST \n\n";
           cout << "0.  EXIT \n\n\n\n";
    
            cout << "Enter a number (#) corresponding to your selection - ";
    
            cin >> Selection;
    
            itoa(Selection, Choice, 2);
    
            clrscr();                               // clears the screen...
    
       }while((isalpha(Choice[0])) || (Selection < 0 || Selection > 5));
    .......
    for some reasong i can't get it to work.... maybe i am using a wrong algorithm in a while loop delimeter...... i am sure there's gotta be a way, i am sure people have run into this problem before when asked for int someone entered a char and the loop crashed...??

    ?? any ideas?

    Regards,
    matheo917

  9. #9
    Registered User matheo917's Avatar
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    anyone care to give another perhaps a different solution??

  10. #10
    Registered User matheo917's Avatar
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    hmmm..... no answers...

    anyone please....

    thank you..

    Regards,
    matheo917

  11. #11
    Registered User
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    Is there any reason you can't do it like this?
    Code:
      char Choice;
      do
       {
           cout << "1.  HELP MENU \n\n";
           cout << "2.  INVENTORY DIRECTORY \n\n";
           cout << "3.  DELIVERY INFORMATION \n\n";
           cout << "4.  ORDERING DIRECTORY \n\n";
           cout << "5.  WAITING LIST \n\n";
           cout << "0.  EXIT \n\n\n\n";
    
            cout << "Enter a number (#) corresponding to your selection - ";
    
            cin >> Choice;
    
            clrscr();                               // clears the screen...
    
       }while(Choice < '0' || Choice > '5');

  12. #12
    Registered User matheo917's Avatar
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    in this particular case the compiler will not detect whether a character is less than the other based on the less than or greater than principal.......at least that's what i think and compiler too i guess....

    i am working on something similar now, although i am making my loop to be infinite ....... here it is:

    Code:
    do
       {
           cout << "1.  HELP MENU \n\n";
           cout << "2.  INVENTORY DIRECTORY \n\n";
           cout << "3.  DELIVERY INFORMATION \n\n";
           cout << "4.  ORDERING DIRECTORY \n\n";
           cout << "5.  WAITING LIST \n\n";
           cout << "0.  EXIT \n\n\n\n";
    
            cout << "Enter a number (#) corresponding to your selection: ";
    
            cin >> Selection;
            Temp2 = Selection;
            Temp1 = (int)Temp2;
            Choice = Temp1;
    
            clrscr();                               // clears the screen...
    
       }while ((Selection < '0' || Selection > '5') || (Choice < 0 || Choice > 5));
    i am thinking of a ASCII representation of these number when it comes to characters i.e. char(32) maybe that will work......

    what do you think?

    Regards,
    matheo917

  13. #13
    Registered User matheo917's Avatar
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    got it to work, however it's not too roboust and too innovative, but i kind of got tired of trying to do it the hard way and so here it goes......

    Code:
    string Selection;
    
      do
       {
           cout << "1.  HELP MENU \n\n";
           cout << "2.  INVENTORY DIRECTORY \n\n";
           cout << "3.  DELIVERY INFORMATION \n\n";
           cout << "4.  ORDERING DIRECTORY \n\n";
           cout << "5.  WAITING LIST \n\n";
           cout << "0.  EXIT \n\n\n\n";
    
            cout << "Enter a number (#) corresponding to your selection: ";
    
            cin >> Selection;
    
        clrscr();
    
       }while ((Selection != "0" && Selection != "1" &&
                Selection != "2" && Selection != "3" &&
                Selection != "4" && Selection != "5"));
    thanks for the effort...


    matheo917

  14. #14
    Registered User
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    in this particular case the compiler will not detect whether a character is less than the other based on the less than or greater than principal.......at least that's what i think and compiler too i guess....
    It does on my computer (Windows NT). But I guess if you're not comfortable with it, go with what feels right.

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