Initializing Int Array With a Non-Zero Value

[simondex]

Hi, Everyone!

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


Thank You Very Much.

Truly Yours, Simon Dexter

 

[John Carson]

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);

 

[Rick N. Backer]

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."

 

[John Carson]

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.

 

[upashu2]

how to initialize an int array with a non-zero number?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.

 

[makc.the.great]

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.

 

[Maxim Yegorushkin]

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]

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

 

[John Carson]

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.

 

[Rick N. Backer]

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."

 

[John Carson]

On 12 Jul 2005 21:46:19 -0700, (e-mail address removed) 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.

 

[Default User]

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

 

[John Carson]

[some further thoughts]

On 12 Jul 2005 21:46:19 -0700, (e-mail address removed) 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.

 

[Rick N. Backer]

[some further thoughts]

On 12 Jul 2005 21:46:19 -0700, (e-mail address removed) 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.

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."