Initializing Int Array With a Non-Zero Value

Discussion in 'C++' started by simondex@yahoo.com, Jul 13, 2005.

  1. Guest

    Hi, Everyone!

    Does anyone know how to initialize an int array with a non-zero number?


    Thank You Very Much.

    Truly Yours, Simon Dexter
     
    , Jul 13, 2005
    #1
    1. Advertising

  2. John Carson Guest

    <> wrote in message
    news:
    > Hi, Everyone!
    >
    > Does anyone know how to initialize an int array with a non-zero
    > number?
    >
    >
    > Thank You Very Much.
    >
    > Truly Yours, Simon Dexter


    Int is not int. C++ is case sensitive.

    The only way to do this at the point of declaration is to repeat the number
    as many times as you need it, e.g.,

    int array[5] = {9,9,9,9,9};

    Alternatively, you can do it in a loop after the declaration.

    Vectors allow you to avoid repeating the number:

    std::vector<int> array(5, 9);


    --
    John Carson
     
    John Carson, Jul 13, 2005
    #2
    1. Advertising

  3. On 12 Jul 2005 21:46:19 -0700, did courageously
    avow:

    >Hi, Everyone!
    >
    >Does anyone know how to initialize an int array with a non-zero number?


    int intArr[n1] = {x1}; // declaration and initialization

    n1 can be any positive integer value and x1 can be any legitimate
    value; number, char, pointer to another array, etc.. I believe you
    don't need to specify all the elements in the list. That said, I
    trust I will be corrected if I'm wrong

    -- OR --

    int intArr[n1]; // declaration
    intArr[0] = x1; // initialization

    It all depends on how far you want to go. You can give it a completer
    list in the first example if you want. Or, you can use a for loop
    that runs through the array index until it has filled the last
    element, using the second statement inside the loop, substituting your
    index variable for the zero and applying whatever number you
    application feels is appropriate for the array.


    >
    >Thank You Very Much.


    You're welcome.

    Ken Wilson

    Amer. Dlx. Tele, Gary Moore LP, LP DC Classic w/P90s,
    Jeff Beck Strat, Morgan OM Acoustic,
    Rick 360/12, Std. Strat (MIM), Mesa 100 Nomad,
    Mesa F-30

    "Goodnight Austin, Texas, wherever you are."
     
    Rick N. Backer, Jul 13, 2005
    #3
  4. John Carson Guest

    "Rick N. Backer" <> wrote in message
    news:
    > On 12 Jul 2005 21:46:19 -0700, did courageously
    > avow:
    >
    >> Hi, Everyone!
    >>
    >> Does anyone know how to initialize an int array with a non-zero
    >> number?

    >
    > int intArr[n1] = {x1}; // declaration and initialization
    >
    > n1 can be any positive integer value and x1 can be any legitimate
    > value; number, char, pointer to another array, etc.. I believe you
    > don't need to specify all the elements in the list. That said, I
    > trust I will be corrected if I'm wrong


    Your code has the effect of initializing the first element of the array to
    x1 and the rest to zero. You also can't use pointer values without a cast.


    --
    John Carson
     
    John Carson, Jul 13, 2005
    #4
  5. upashu2 Guest

    >> how to initialize an int array with a non-zero number?
    >> John Carson .....
    >> first element of the array to x1 and the rest to zero

    if we write, int a[20]; it leaves the whole array uninintialized. It
    doesn't initalize array with 0's at all. after all it is c++, not java
    or vb.
    if we write int a[20]={ 1,2};
    then it will initialize only first two elements, and leave all others
    uninitialized.
    Still if you want to initialize an array with 0's, you have to write it
    expilicitly.
    int a[3]={0,0,0}; or use std::vector, std::vector<int> a(size,0);
    The answer is whether u want to initialize array with zero or non-zero
    value , you have to explicitly initialize them.
     
    upashu2, Jul 13, 2005
    #5
  6. Guest

    > Does anyone know how to initialize an int array with a non-zero number?

    did anyone mention memset?

    like, int * pi = new int (123);
    memset(pi, <some byte here>, 123*sizeof(int));

    pity you'd have pretty limited initial values set to choose from.
     
    , Jul 13, 2005
    #6
  7. On Wed, 13 Jul 2005 11:44:15 +0400, upashu2 <> wrote:

    >>> how to initialize an int array with a non-zero number?
    >>> John Carson .....
    >>> first element of the array to x1 and the rest to zero

    > if we write, int a[20]; it leaves the whole array uninintialized. It
    > doesn't initalize array with 0's at all. after all it is c++, not java
    > or vb.
    > if we write int a[20]={ 1,2};
    > then it will initialize only first two elements, and leave all others
    > uninitialized.


    This is wrong.

    [dcl.init.aggr] 8.5.1 Aggregates
    ....
    7 If there are fewer initializers in the list than there are members in
    the aggregate, then each member not explicitly initialized shall be
    value-initialized (8.5).
    [Example:
    struct S { int a; char* b; int c; };
    S ss = { 1, "asdf" };
    initializes ss.a with 1, ss.b with "asdf", and ss.c with the value of an
    expression of the form int(), that is, 0. ]

    --
    Maxim Yegorushkin
    <>
     
    Maxim Yegorushkin, Jul 13, 2005
    #7
  8. On Wed, 13 Jul 2005 08:46:19 +0400, <> wrote:

    > Does anyone know how to initialize an int array with a non-zero number?


    Just iterate over the array and initialize its members with any values you
    like.

    The standard library provides some basic function templates for filling
    arrays as well as ranges:

    fill/fill_n
    generate

    Example:

    int a[10];
    fill_n(a, sizeof(a) / sizeof(*a), 1); // fill with ones

    --
    Maxim Yegorushkin
    <>
     
    Maxim Yegorushkin, Jul 13, 2005
    #8
  9. John Carson Guest

    <> wrote in message
    news:
    >> Does anyone know how to initialize an int array with a non-zero
    >> number?

    >
    > did anyone mention memset?
    >
    > like, int * pi = new int (123);


    That should be

    int *pi = new int[123];

    > memset(pi, <some byte here>, 123*sizeof(int));


    This does byte by byte initialisation, which is viable for the very small
    fraction of integers which have the same number in each byte.

    > pity you'd have pretty limited initial values set to choose from.


    Small and obsure. You cannot do this:

    memset(pi, 5, 123*sizeof(int));

    and initialise all integers to 5. You initialise all integers to whatever
    number consists of a 5 in each byte.

    --
    John Carson
     
    John Carson, Jul 13, 2005
    #9
  10. On Wed, 13 Jul 2005 15:46:54 +1000, "John Carson"
    <> did courageously avow:

    >"Rick N. Backer" <> wrote in message
    >news:
    >> On 12 Jul 2005 21:46:19 -0700, did courageously
    >> avow:
    >>
    >>> Hi, Everyone!
    >>>
    >>> Does anyone know how to initialize an int array with a non-zero
    >>> number?

    >>
    >> int intArr[n1] = {x1}; // declaration and initialization
    >>
    >> n1 can be any positive integer value and x1 can be any legitimate
    >> value; number, char, pointer to another array, etc.. I believe you
    >> don't need to specify all the elements in the list. That said, I
    >> trust I will be corrected if I'm wrong

    >
    >Your code has the effect of initializing the first element of the array to
    >x1 and the rest to zero. You also can't use pointer values without a cast.


    Where is this pointer you speak of?
    I see an int array being initialized to hold n1 elements of which the
    first will be x1 and the rest zero as you say. If you had all my post
    here, you would see I also explained how to declare all the members at
    once if the OP so wished, how to declare an array without
    initialization and then initialize a single element later, and also
    suggest how it could be done in a for loop. Why are you centering on
    one item and not the whole post?


    Ken Wilson

    Amer. Dlx. Tele, Gary Moore LP, LP DC Classic w/P90s,
    Jeff Beck Strat, Morgan OM Acoustic,
    Rick 360/12, Std. Strat (MIM), Mesa 100 Nomad,
    Mesa F-30

    "Goodnight Austin, Texas, wherever you are."
     
    Rick N. Backer, Jul 13, 2005
    #10
  11. John Carson Guest

    "Rick N. Backer" <> wrote in message
    news:
    > On Wed, 13 Jul 2005 15:46:54 +1000, "John Carson"
    > <> did courageously avow:
    >
    >> "Rick N. Backer" <> wrote in message
    >> news:
    >>> On 12 Jul 2005 21:46:19 -0700, did courageously
    >>> avow:
    >>>
    >>>> Hi, Everyone!
    >>>>
    >>>> Does anyone know how to initialize an int array with a non-zero
    >>>> number?
    >>>
    >>> int intArr[n1] = {x1}; // declaration and initialization
    >>>
    >>> n1 can be any positive integer value and x1 can be any legitimate
    >>> value; number, char, pointer to another array, etc.. I believe you
    >>> don't need to specify all the elements in the list. That said, I
    >>> trust I will be corrected if I'm wrong

    >>
    >> Your code has the effect of initializing the first element of the
    >> array to x1 and the rest to zero. You also can't use pointer values
    >> without a cast.

    >
    > Where is this pointer you speak of?


    You say: "x1 can be any legitimate value; number, char, pointer to another
    array, etc". Thus the "pointer to another array" is the pointer that I speak
    of. x1 cannot be a pointer without using a cast.

    > I see an int array being initialized to hold n1 elements of which the
    > first will be x1 and the rest zero as you say. If you had all my post
    > here, you would see I also explained how to declare all the members at
    > once if the OP so wished, how to declare an array without
    > initialization and then initialize a single element later, and also
    > suggest how it could be done in a for loop. Why are you centering on
    > one item and not the whole post?


    The OP asked how to initialize an array with a non-zero number. I took this
    to mean initialize the *whole* array with a non-zero number and so I took
    your answer to be a claim that

    int intArr[n1] = {x1};

    initialized each element in the array to x1. The fact that you also gave
    alternative methods of initialization was not inconsistent with this
    interpretation.

    If my interpretation was incorrect, I apologize.

    --
    John Carson
     
    John Carson, Jul 13, 2005
    #11
  12. Default User Guest

    upashu2 wrote:
    > >> how to initialize an int array with a non-zero number?
    > >> John Carson .....
    > >> first element of the array to x1 and the rest to zero


    > if we write, int a[20]; it leaves the whole array uninintialized. It
    > doesn't initalize array with 0's at all. after all it is c++, not java
    > or vb.


    That's true, but not what John presented. He initialized the first
    value. The rest of the array will be default initialized.

    > if we write int a[20]={ 1,2};
    > then it will initialize only first two elements, and leave all others
    > uninitialized.


    You are incorrect. The rest of the array will be filled with 0.

    > Still if you want to initialize an array with 0's, you have to write it
    > expilicitly.


    Wrong.




    Brian
     
    Default User, Jul 13, 2005
    #12
  13. John Carson Guest

    [some further thoughts]

    "Rick N. Backer" <> wrote in message
    news:
    > On Wed, 13 Jul 2005 15:46:54 +1000, "John Carson"
    > <> did courageously avow:
    >
    >> "Rick N. Backer" <> wrote in message
    >> news:
    >>> On 12 Jul 2005 21:46:19 -0700, did courageously
    >>> avow:
    >>>
    >>>> Hi, Everyone!
    >>>>
    >>>> Does anyone know how to initialize an int array with a non-zero
    >>>> number?
    >>>
    >>> int intArr[n1] = {x1}; // declaration and initialization
    >>>
    >>> n1 can be any positive integer value and x1 can be any legitimate
    >>> value; number, char, pointer to another array, etc.. I believe you
    >>> don't need to specify all the elements in the list. That said, I
    >>> trust I will be corrected if I'm wrong

    >>
    >> Your code has the effect of initializing the first element of the
    >> array to x1 and the rest to zero. You also can't use pointer values
    >> without a cast.

    >
    > Where is this pointer you speak of?
    > I see an int array being initialized to hold n1 elements of which the
    > first will be x1 and the rest zero as you say. If you had all my post
    > here, you would see I also explained how to declare all the members at
    > once if the OP so wished, how to declare an array without
    > initialization and then initialize a single element later, and also
    > suggest how it could be done in a for loop.


    You didn't say at *any* point in your post that

    int intArr[n1] = {x1};

    would set all elements after the first to zero, so it was surely worth
    pointing it out so the OP would know what to expect.

    > Why are you centering on one item and not the whole post?


    I was not writing a review. It is perfectly legitimate to focus on the one
    part of a post that is in need of clarification.

    --
    John Carson
     
    John Carson, Jul 13, 2005
    #13
  14. On Thu, 14 Jul 2005 03:25:54 +1000, "John Carson"
    <> did courageously avow:

    >[some further thoughts]
    >
    >"Rick N. Backer" <> wrote in message
    >news:
    >> On Wed, 13 Jul 2005 15:46:54 +1000, "John Carson"
    >> <> did courageously avow:
    >>
    >>> "Rick N. Backer" <> wrote in message
    >>> news:
    >>>> On 12 Jul 2005 21:46:19 -0700, did courageously
    >>>> avow:
    >>>>
    >>>>> Hi, Everyone!
    >>>>>
    >>>>> Does anyone know how to initialize an int array with a non-zero
    >>>>> number?
    >>>>
    >>>> int intArr[n1] = {x1}; // declaration and initialization
    >>>>
    >>>> n1 can be any positive integer value and x1 can be any legitimate
    >>>> value; number, char, pointer to another array, etc.. I believe you
    >>>> don't need to specify all the elements in the list. That said, I
    >>>> trust I will be corrected if I'm wrong
    >>>
    >>> Your code has the effect of initializing the first element of the
    >>> array to x1 and the rest to zero. You also can't use pointer values
    >>> without a cast.

    >>
    >> Where is this pointer you speak of?
    >> I see an int array being initialized to hold n1 elements of which the
    >> first will be x1 and the rest zero as you say. If you had all my post
    >> here, you would see I also explained how to declare all the members at
    >> once if the OP so wished, how to declare an array without
    >> initialization and then initialize a single element later, and also
    >> suggest how it could be done in a for loop.

    >
    >You didn't say at *any* point in your post that
    >
    >int intArr[n1] = {x1};
    >
    >would set all elements after the first to zero, so it was surely worth
    >pointing it out so the OP would know what to expect.


    I have no problem and readily concede that point and, truthfully,
    hadn't considered that aspect. I may have boiled the question down to
    much in trying to simplify it and my response.
    >
    >> Why are you centering on one item and not the whole post?

    >
    >I was not writing a review. It is perfectly legitimate to focus on the one
    >part of a post that is in need of clarification.


    Oh how I hate first encounters :). I am used to people only
    applying to one point and will concede this also and stand now
    unoffended. I am just used to people interjecting in line and
    returning the original document intact so context of the discussion
    can be maintained. In this instance I ass-u-me'd, incorrectly, that
    you hadn't paid attention to the rest of the post. My apologies.


    Ken Wilson

    Amer. Dlx. Tele, Gary Moore LP, LP DC Classic w/P90s,
    Jeff Beck Strat, Morgan OM Acoustic,
    Rick 360/12, Std. Strat (MIM), Mesa 100 Nomad,
    Mesa F-30

    "Goodnight Austin, Texas, wherever you are."
     
    Rick N. Backer, Jul 13, 2005
    #14
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Schnoffos
    Replies:
    2
    Views:
    1,247
    Martien Verbruggen
    Jun 27, 2003
  2. Hal Styli
    Replies:
    14
    Views:
    1,697
    Old Wolf
    Jan 20, 2004
  3. Replies:
    23
    Views:
    867
    Chris Thomasson
    Aug 29, 2007
  4. Replies:
    6
    Views:
    1,590
    Richard Tobin
    Mar 19, 2009
  5. Alain Spineux
    Replies:
    6
    Views:
    653
    Eric Sosman
    May 17, 2011
Loading...

Share This Page