Suppose we want to return a long integer by a function. How to do it? Is it valid?
long int function()
{
long int b;
b=1000000000;
return b;
}
Asked
Active
Viewed 8,805 times
3
Christopher Bottoms
- 11,218
- 8
- 50
- 99
Vasu Dev Garg
- 121
- 1
- 15
4 Answers
12
Yes, it is valid.
As long as you're retuning a proper long int value (which we can see, you're doing#) and catching that into another long int (you need to take care), it should be fine.
#) As per the C11 standard, LONG_MAX is +2147483647 and 1000000000 is less than that. Chapter §5.2.4.2.1, for reference.
Natasha Dutta
- 3,242
- 21
- 23
-
2Plus one for standard quotation. – Bathsheba May 20 '15 at 12:19
-
@Bathsheba Appreciate that!! Gracious. :-) – Natasha Dutta May 20 '15 at 12:20
-
I don't quite see what the value limits of a long have to do with the question. – Lundin May 20 '15 at 12:54
-
I conject that Natasha, like me, wanted to examine the validity of the assignment `b=1000000000`. – Bathsheba May 20 '15 at 13:03
-
@Bathsheba I read the question as "is it valid to return a long integer from a function", rather than "does the code in this example have well-defined behavior". Anyway, no biggie. – Lundin May 20 '15 at 13:07
6
Can long int be returned by a function in c?
Persixty
- 8,165
- 2
- 13
- 35
-
Apologies to the three detractors who clearly think I'm lowering the tone. But I and two others thought it was funny. So I'm saying the jury is still out on this one. – Persixty May 22 '15 at 09:30
-
This answer continues to divide opinion but at least those in favour now out number those against. – Persixty Jun 09 '15 at 16:48
2
The C standard stipulates a minimum size of 32 bits for a long int, stored in such a way as to guarantee that values in the range [−2147483647, +2147483647] can be represented. (Note that a 2s compliment representation gives you −2147483648). So the assignment of 1,000,000,000 to a long int is always defined.
Returning a value copy of a long int is well-defined too.
Note that if you hadn't initialised b (i.e. if you had omitted the statement b=1000000000;), then the behaviour of your program would have been undefined.
Bathsheba
- 231,907
- 34
- 361
- 483
-
I don't quite see what the value limits of a long have to do with the question. – Lundin May 20 '15 at 12:54
-
How could you? I upvoted your answer :-) Seriously, it would have been very relevant had the OP, say had wanted to assign 10,000,000,000 to the `long int`. That's not always well-defined. – Bathsheba May 20 '15 at 12:55
-
The type of the integer literal itself is the smallest possible that can fit the number, for the given system. But it is never smaller than `int`. This is well-defined in 6.4.4.1. In case of 10 billion, the compiler would likely pick type `long long int`. If you then show that into a long, the following applies (6.3.1.3) `"Otherwise, the new type is signed and the value cannot be represented in it; either the result is implementation-defined or an implementation-defined signal is raised."`. So something implementation-defined is guaranteed to happen. – Lundin May 20 '15 at 13:04
2
A function can return pretty much any type:
6.9.1
The return type of a function shall be void or a complete object type other than array type.
And that's it.
Lundin
- 195,001
- 40
- 254
- 396