Having trouble with C++, can't cout << 100000 * 100000 correctly

Question

I can't print 100000 * 100000 when I use COUT in C++. The output was 1410065408 instead of 10000000000. How can I fix that? Thanks!

`10000000000` is larger than an `int` you need to use a larger data type — Alan Birtles, Jul 14 '21 at 06:44
If you enabled [compiler warnings](https://stackoverflow.com/questions/57842756/why-should-i-always-enable-compiler-warnings) you would probably have seen the problem right away. — n. 1.8e9-where's-my-share m., Jul 14 '21 at 06:59

score 5 · Answer 1 · edited Jul 14 '21 at 06:41

5

By default, integer literals are of type int which causes the overflow you have. Use 100000LL to mark the number as long long and have a long long result.

https://en.cppreference.com/w/cpp/language/integer_literal

edited Jul 14 '21 at 06:41

463035818_is_not_a_number

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answered Jul 14 '21 at 06:40

Michael Chourdakis

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paradocslover is not a factual sentence, but yours is. Anyways, i found the answer on your profile. So nvm – paradocslover Jul 14 '21 at 06:45
The best discussion that i have had on SO so far :lol: – paradocslover Jul 14 '21 at 08:11

prehistoricpenguin · Accepted Answer · 2021-07-14T07:00:43.207

1

The value is truncated since 10000000000 is larger than the default interger type int max value (std::numeric_limit<int>::max()) ,

hex(10000000000) = 0x2540be400
hex(1410065408) =   0x540be400

You can see that the first byte is truncated.

To fix it:

100000LL * 100000

or cast it

static_cast<int64_t>(100000) * 100000

edited Jul 14 '21 at 07:00

answered Jul 14 '21 at 06:46

prehistoricpenguin

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Having trouble with C++, can't cout << 100000 * 100000 correctly

2 Answers2