using a for loop to determine maximum value of an int variable

[garyusenet]

I'm trying to investigate the maximum size of different variable types.
I'm using INT as my starting variable for exploration. I know that the
maximum number that the int variable can take is: 65,535. But i'm
trying to write a program to test this, assuming I didn't know this
number in advance. I came up with the following but have two questions.
Maybe someone can help?

using System;
using System.Collecti ons.Generic;
using System.Text;

namespace ConsoleApplicat ion1
{
class Program
{
static void Main(string[] args)
{
int j = 0;
double i = 0;
for (i = 0; i < 999999999999999 9999; i++)
{

j = (int)i;
Console.WriteLi ne(j.ToString() );
///on error console.write(t here was an error... this
was the error code)

}
}
}
}

q.1.
I want to have an idea of what is going on in my program. As you can
see, in my for loop I am writing the value of j to the screen on a new
line every time it is incremented. This is too slow. It seems to be
taking forever to scroll through the digits. My question is, is there a
way that I can display the value of j every, say, 10 thousand
increments?

q.2.
is there a way I can time how long the loop takes to complete, and at
the end of the loop display this time?

q.3
I'd like to output an error message to the screen when the variable
crashes because it's too small to hold the number being allocated to
it. How do i do this?

Thankyou,

Gary.

[Dustin Campbell]

I'm trying to investigate the maximum size of different variable

types. I'm using INT as my starting variable for exploration. I know
that the maximum number that the int variable can take is: 65,535.

Actually, that's the maximum size of a ushort. int has a maximum upper limit
of 2,147,483,647. In fact, you can see the upper limit by checking the MaxValue
field of int.

But i'm trying to write a program to test this, assuming I didn't know
this number in advance. I came up with the following but have two
questions. Maybe someone can help?

using System;
using System.Collecti ons.Generic;
using System.Text;
namespace ConsoleApplicat ion1
{
class Program
{
static void Main(string[] args)
{
int j = 0;
double i = 0;
for (i = 0; i < 999999999999999 9999; i++)
{
j = (int)i;
Console.WriteLi ne(j.ToString() );
///on error console.write(t here was an error... this
was the error code)
}
}
}
}
q.1.
I want to have an idea of what is going on in my program. As you can
see, in my for loop I am writing the value of j to the screen on a new
line every time it is incremented. This is too slow. It seems to be
taking forever to scroll through the digits. My question is, is there
a
way that I can display the value of j every, say, 10 thousand
increments?

sure. i += 10000

q.2.
is there a way I can time how long the loop takes to complete, and at
the end of the loop display this time?

If you're in .NET 2.0, try the System.Diagnost ics.Stopwatch class.

q.3
I'd like to output an error message to the screen when the variable
crashes because it's too small to hold the number being allocated to
it. How do i do this?

Well, you shouldn't actually need to do this. It'll crash on its own and
display an error message to the console. However, you could wrap your code
in a try/catch block like this:

static void Main(string[] args)
{
try
{
// Your code here...
}
catch (Exception ex)
{
Console.WriteLi ne(ex.Message);
}
}

Best Regards,
Dustin Campbell
Developer Express Inc.

[Bobbo]

ga********@mywa y.com wrote:

I'm trying to investigate the maximum size of different variable types.

If you're trying to figure out which data types are best for storing
certain data, try this reference table:
http://msdn2.microsoft.com/en-us/library/exx3b86w.aspx

[garyusenet]

Thankyou very much Dustin your answers have answerd 90% of my questions
and have really helped me alot.

Although changing the for interation from 1, to a higher number works
for this test it doesn't really answer my for loop question, which was
probabally because I didn't put my question right in the first
instance! I was intrigued about the question when it came to me in this
example and still dont really know the answer.

My First Question is: -

With a for loop like so: -

for(i=0; i<9999999999; i++)
{

}

how can I do an action every nth interations of the loop? so for
instance everytime the loop has executed 10,000 times do something?

Also another question has come to me now as I have worked through your
answers.
My code is now displaying the value of of the integer variable to
screen and I'm not having to wait as long as i am incrementing it's
value by 500,000 every iteration. However. When the value gets to:
2145,000,000 all future increments don't generate an error.
Instead each future increment is displayed as: -2147483648.

I'm just wondering why an error isn't generated. And why the value
becomes negative, with a numerical value one greater than the actual
numerical value that the variable is permitted to hold?

Thanks!

Gary-

Dustin Campbell wrote:

I'm trying to investigate the maximum size of different variable
types. I'm using INT as my starting variable for exploration. I know
that the maximum number that the int variable can take is: 65,535.

Actually, that's the maximum size of a ushort. int has a maximum upper limit
of 2,147,483,647. In fact, you can see the upper limit by checking the MaxValue
field of int.

But i'm trying to write a program to test this, assuming I didn't know
this number in advance. I came up with the following but have two
questions. Maybe someone can help?

using System;
using System.Collecti ons.Generic;
using System.Text;
namespace ConsoleApplicat ion1
{
class Program
{
static void Main(string[] args)
{
int j = 0;
double i = 0;
for (i = 0; i < 999999999999999 9999; i++)
{
j = (int)i;
Console.WriteLi ne(j.ToString() );
///on error console.write(t here was an error... this
was the error code)
}
}
}
}
q.1.
I want to have an idea of what is going on in my program. As you can
see, in my for loop I am writing the value of j to the screen on a new
line every time it is incremented. This is too slow. It seems to be
taking forever to scroll through the digits. My question is, is there
a
way that I can display the value of j every, say, 10 thousand
increments?

sure. i += 10000

q.2.
is there a way I can time how long the loop takes to complete, and at
the end of the loop display this time?

If you're in .NET 2.0, try the System.Diagnost ics.Stopwatch class.

q.3
I'd like to output an error message to the screen when the variable
crashes because it's too small to hold the number being allocated to
it. How do i do this?

Well, you shouldn't actually need to do this. It'll crash on its own and
display an error message to the console. However, you could wrap your code
in a try/catch block like this:

static void Main(string[] args)
{
try
{
// Your code here...
}
catch (Exception ex)
{
Console.WriteLi ne(ex.Message);
}
}

Best Regards,
Dustin Campbell
Developer Express Inc.

[mc]

how about: -

using System;
using System.Collecti ons.Generic;
using System.Text;

namespace ConsoleApplicat ion1
{
class Program
{
static void Main(string[] args)
{
Console.WriteLi ne("Int32 Max= "+Int32.MaxValu e.ToString());
}
}
}

I know it's a bit tongue and cheek, but surely this is all you trying to
achieve?

The MaxValue and MinValue constants are available for all sorts of
different variable types.

MC

ga********@mywa y.com wrote:

I'm trying to investigate the maximum size of different variable types.
I'm using INT as my starting variable for exploration. I know that the
maximum number that the int variable can take is: 65,535. But i'm
trying to write a program to test this, assuming I didn't know this
number in advance. I came up with the following but have two questions.
Maybe someone can help?

using System;
using System.Collecti ons.Generic;
using System.Text;

namespace ConsoleApplicat ion1
{
class Program
{
static void Main(string[] args)
{
int j = 0;
double i = 0;
for (i = 0; i < 999999999999999 9999; i++)
{

j = (int)i;
Console.WriteLi ne(j.ToString() );
///on error console.write(t here was an error... this
was the error code)

}
}
}
}

q.1.
I want to have an idea of what is going on in my program. As you can
see, in my for loop I am writing the value of j to the screen on a new
line every time it is incremented. This is too slow. It seems to be
taking forever to scroll through the digits. My question is, is there a
way that I can display the value of j every, say, 10 thousand
increments?

q.2.
is there a way I can time how long the loop takes to complete, and at
the end of the loop display this time?

q.3
I'd like to output an error message to the screen when the variable
crashes because it's too small to hold the number being allocated to
it. How do i do this?

Thankyou,

Gary.

[Tom Porterfield]

ga********@mywa y.com wrote:

I'm trying to investigate the maximum size of different variable types.
I'm using INT as my starting variable for exploration. I know that the
maximum number that the int variable can take is: 65,535. But i'm
trying to write a program to test this, assuming I didn't know this
number in advance. I came up with the following but have two questions.
Maybe someone can help?

using System;
using System.Collecti ons.Generic;
using System.Text;

namespace ConsoleApplicat ion1
{
class Program
{
static void Main(string[] args)
{
int j = 0;
double i = 0;
for (i = 0; i < 999999999999999 9999; i++)
{

j = (int)i;
Console.WriteLi ne(j.ToString() );
///on error console.write(t here was an error... this
was the error code)

}
}
}
}

To start with, System.Int16, Int32 and Int64 all have a static MaxValue
property. Accessing that is much faster than looping until an exception is
thrown.

q.1.
I want to have an idea of what is going on in my program. As you can
see, in my for loop I am writing the value of j to the screen on a new
line every time it is incremented. This is too slow. It seems to be
taking forever to scroll through the digits. My question is, is there a
way that I can display the value of j every, say, 10 thousand
increments?

if (j%10000 == 0)Console.Write Line(j.ToString ());

q.2.
is there a way I can time how long the loop takes to complete, and at
the end of the loop display this time?

As Dustin responded, System.Diagnost ics.Stopwatch should help. If not .NET
2.0, you could create a DateTime object at the start of the loop, another at
the end, set both values to the static DateTime.Now and subract end from
start once the loop is finished. Ex:

DateTime start = DateTime.Now;
for ()
{
....
}
Console.WriteLi ne (DateTime.Now - start);

q.3
I'd like to output an error message to the screen when the variable
crashes because it's too small to hold the number being allocated to
it. How do i do this?

The problem here is it won't crash. if you try to cast a value that is too
large for an Int32 into an Int32, it simply loops. Try the following in
code:

double d = double.MaxValue
int x = (int)d;

This will not cause an exception and will instead set the value of x
to -2147483648. So you would need to check for a negative number and then
behave accordingly. Ex:

if (j < 0)
{
Console.WriteLi ne ("Max value is " + (i - 1));
break;
}

But again, System.Int32.Ma xValue is the better way to get this value.
--
Tom Porterfield

[Dustin Campbell]

Thankyou very much Dustin your answers have answerd 90% of my

questions and have really helped me alot.

Although changing the for interation from 1, to a higher number works
for this test it doesn't really answer my for loop question, which was
probabally because I didn't put my question right in the first
instance! I was intrigued about the question when it came to me in
this example and still dont really know the answer.

My First Question is: -

With a for loop like so: -

for(i=0; i<9999999999; i++)
{
}

how can I do an action every nth interations of the loop? so for
instance everytime the loop has executed 10,000 times do something?

Use modular arithmetic like this:

for(i=0; i<9999999999; i++)
{
if (i % 10000 == 0)
// do something...
}

Also another question has come to me now as I have worked through your
answers.
My code is now displaying the value of of the integer variable to
screen and I'm not having to wait as long as i am incrementing it's
value by 500,000 every iteration. However. When the value gets to:
2145,000,000 all future increments don't generate an error.
Instead each future increment is displayed as: -2147483648.
I'm just wondering why an error isn't generated. And why the value
becomes negative, with a numerical value one greater than the actual
numerical value that the variable is permitted to hold?

See Tom's excellent post on this thread.

Best Regards,
Dustin Campbell
Developer Express Inc.

[garyusenet]

Thankyou these are exactly the answers I was looking for. I have two
final questions on the subject maybe someone would be kind enough to
answer them for me.

1.
Why isn't an error generated? Is this a floor with the .net error
checking?

2.
When I experiment with a uint instead of an int, and increment it by
500,000 at a time, i notice the value outputted to the console doesn't
steadily increase, but increases, then decreases, then increases etc...
why is this? what is going on?

Thanks,

Gary-

[Marc Gravell]

how can I do an action every nth interations of the loop?

for(...) {
if(i % 10000==0) {
DoSomethingInte resting();
}
}
// perhaps DoSomethingInte resting() here if you always
// want it to fire at the end even if partly through a block

Marc

[Dustin Campbell]

Thankyou these are exactly the answers I was looking for. I have two

final questions on the subject maybe someone would be kind enough to
answer them for me.

1.
Why isn't an error generated? Is this a floor with the .net error
checking?

Try wrapping the expression with the "checked" keyword. This will cause the
runtime to throw an OverflowExcepti on.

j = checked((int)i) ;

2.
When I experiment with a uint instead of an int, and increment it by
500,000 at a time, i notice the value outputted to the console doesn't
steadily increase, but increases, then decreases, then increases
etc...
why is this? what is going on?

The uint variable is overflowing and then being set to 0 + the overflow amount.
For example:

Best Regards,
Dustin Campbell
Developer Express Inc.