Thread: Appending charaters to a char*

  1. #1
    Registered User
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    Nov 2006

    Question Appending charaters to a char*

    I'm a newbie to C++. Infact I started to code my first C++ programme today and I need some assistance to get me going.

    I basically want to know, how do I read characters from a text file and append the characters to a char*

    The reason I need a char* is because my constructor requires a char* to instantiate an object. The class has only one private variable of type char* this is because the series of characters (aka. string) will be of variable amount.

    Please help. Thanks.

    Edit: I'm not expecting a complete solution but snippets or guidance.
    Last edited by masterblix; 11-21-2006 at 02:53 PM.

  2. #2
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    Jan 2005
    >> I started to code my first C++ programme today
    IMO, your first C++ program should use the C++ string class. Using char* is C style and is generally not recommended in C++ programs, despite the fact that it is unfortunately taught by many books, tutorials, and instructors.

    As to your question, the answer depends. If the char* already has enough space and you are appending only a single character, you can set the last character to your new character and assign '\0' (the terminating null) to the next spot in the array. If your char* does not have enough space, you need to create a temporary char* with a larger size, then copy over the original string, then append the character as above. Then delete the old array, and assign the temporary pointer to the member variable.

    If you are reading characters from a file, you can read more than one character at a time and append them all at once. If the char* has enough room for the new characters, you can use strcat to concatenate the new string to the old one. If the char* is too small to hold the combined string, you have to reallocate space for it as I mentioned above.

    If you were using the C++ string class, you would just use myString += newChar. That's a big reason why it is preferred.

  3. #3
    Frequently Quite Prolix dwks's Avatar
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    Apr 2005
    C++ file tutorial:

    You open a file stream, which you can treat like cin or cout (depending on the type).

    C-string tutorial:
    C++ string class tutorial:

    Tutorial page:

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  4. #4
    Registered User
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    Nov 2006

    Thumbs up

    Thanks Daved and dwks.

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