Here I would like to mention the concept of integer clock.
The maximum and minimum values for int in Java are:
int MAX_VALUE = 2147483647
int MIN_VALUE = -2147483648
Please check the following results
int a = 2147483645;
for(int i=0; i<10; i++) {
System.out.println("a:" + a++);
}
Output:
a:2147483645
a:2147483646
a:2147483647
a:-2147483648
a:-2147483647
a:-2147483646
a:-2147483645
a:-2147483644
a:-2147483643
a:-2147483642
It shows that when you go beyond the limit of the +ve range of integer, the next values starts from its negative starting value again.
-2147483648, <-----------------
-2147483647, |
-2147483646, |
. |
. |
. | (the next value will go back in -ve range)
0, |
+1, |
+2, |
+3, |
. |
. |
., |
+2147483645, |
+2147483646, |
+2147483647 ---------------------
If you calculate the factorial of 13 it is 6227020800. This value goes beyond the int range of java. So the new value will be
6227020800
- 2147483647 (+ve max value)
-----------------
Value = 4079537153
- 2147483648 (-ve max value)
-----------------
value = 1932053505
- 1 (for zero in between -ve to +ve value)
----------------
Answer = 1932053504
So, in your answer, the factorial of 13 is becoming 1932053504. This is how integer clock works.
You can use long datatype instead of integer to achieve your purpose.
Answer from Jay on Stack OverflowHere I would like to mention the concept of integer clock.
The maximum and minimum values for int in Java are:
int MAX_VALUE = 2147483647
int MIN_VALUE = -2147483648
Please check the following results
int a = 2147483645;
for(int i=0; i<10; i++) {
System.out.println("a:" + a++);
}
Output:
a:2147483645
a:2147483646
a:2147483647
a:-2147483648
a:-2147483647
a:-2147483646
a:-2147483645
a:-2147483644
a:-2147483643
a:-2147483642
It shows that when you go beyond the limit of the +ve range of integer, the next values starts from its negative starting value again.
-2147483648, <-----------------
-2147483647, |
-2147483646, |
. |
. |
. | (the next value will go back in -ve range)
0, |
+1, |
+2, |
+3, |
. |
. |
., |
+2147483645, |
+2147483646, |
+2147483647 ---------------------
If you calculate the factorial of 13 it is 6227020800. This value goes beyond the int range of java. So the new value will be
6227020800
- 2147483647 (+ve max value)
-----------------
Value = 4079537153
- 2147483648 (-ve max value)
-----------------
value = 1932053505
- 1 (for zero in between -ve to +ve value)
----------------
Answer = 1932053504
So, in your answer, the factorial of 13 is becoming 1932053504. This is how integer clock works.
You can use long datatype instead of integer to achieve your purpose.
Please run this code:
System.out.println("Minimum value of Integer is: " + Integer.MIN_VALUE);
System.out.println("Maximum value of Integer is: " + Integer.MAX_VALUE);
So you can see why it fails.
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The most popular reason is simply that having additional types is more work for the authors of compilers and libraries. Every feature starts with -100 points, and only gets implemented when there's a compelling reason to do so.
In low-level languages like C, automatic bounds-checking was deliberately avoided because it was seen as inefficient. Better to let a program crash with a segfault or divide-by-zero error than to waste precious CPU instructions validating conditions that the programmer should have already explicitly checked.
If you do implement range types, you'll have to figure out the semantics of doing arithmetic on them. So, using your example of a: 10..20 and b: 5..7, you'd need:
a + b: 15..27a - b: 3..15a * b: 50..140a / b: 1..4
What happens if you define c : 1..100 and then write c = a * b;? Do you give a compile-time error? Throw an exception at runtime if a * b > 100?
Moreover, a lot of real-world values just don't have well-defined bounds. For example, if you're writing a Date class based on the Gregorian calendar, defining month: 1..12 and day: 1..31 seems obvious, but what bounds do you put on year? Do you start with 0, 1, 1601, 1753, 1900, 1970, 2000, or -3760? Do you end with 2038, 2099, 2999, or 9999? You'd have to make an arbitrary decision.
It's just easier to use plain int.
In addition to the other fine answers, I'll note that many languages outsource their underlying type system to a "lowest common denominator" type system provided by a runtime, and then layer some small additional features on top of that. The languages of the .NET runtime all have basically the same type system with minor variations; similarly for the JVM languages, and so on.
This has pros and cons for the language designer. On the pro side, if you like the type system then you save on time and effort designing one. On the con side, we spent a fair amount of time on the C# team asking "why does the verifier not like this typesafe-in-C# program?" and discovering that there was some subtle rule of the runtime's type verifier that we were violating.
But the big benefit for a platforms company like Microsoft is interoperability between languages: that you can write libraries in one language and use them in any compatible language.
That then leads to the big cost: what happens when two or more languages disagree on the design for a type not represented in the underlying type system, or represented in a way that doesn't meet all the needs of a particular language? We saw this play out between C# and F# over some decades as the designs for various kinds of tuple types evolved.
If the designers of C# wanted to add ranged integers -- and it's an entirely reasonable suggestion on the face of it -- one of the first pushbacks they'd give you is "will adding this feature to C# create work for the runtime team, the F# team, or anyone else who provides a language in this ecosystem?"
Creating work for others is a lot of points against a feature, particularly when there are potential new features that produce benefits for maintainers of other languages in the ecosystem, rather than costs.
I am making a math workout program and I need to prompt the user to input what digit range would he want in his math problem (using numbers from 0 to 9, from 10 to 100...).
I thought about making an int array (say I want addition problems that user numbers no bigger than 100 and no smaller than 0, id write int[] range = {0, 100}).
Then id use that array in generating numbers for the problem.
Is this the best way?
You could add spacing ;)
if (i > 0 && i < 100)
For those using commons lang an option is to use Range:
Range<Integer> myRange = Range.between(100, 500);
if (myRange.contains(200)){
// do something
}
Also see: how to construct a apache commons 3.1 Range<Integer> object