Cutest bug you have ever seen?

Quote:

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Originally Posted by Hobson

I was getting incorrect results although it was guaranted there should be no overflow for unsigned long long type. Still, result was incorrect. Find an error and get a rep point from me :)

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I know! :D
this is pretty simple to me, but I am not a pro ;).

Code:

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#include <iostream>
#include <string>

using namespace std;

int main()
{
        string s = "Testing";

        //iterate through string backwards
        for(size_t pos = s.length() - 1; ; --pos) {
                cout << s[pos] << endl;;
                if(pos == 0) break;

        }
}

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Code:

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#include <iostream>
#include <string>
#include <vector>
#include <numeric>
#include <algorithm>

using namespace std;

int main()
{
        vector<unsigned long long> vec;
        vec.push_back(123456789012LL);
        vec.push_back(987654321098LL);

        unsigned long long result = accumulate(vec.begin(), vec.end(), 0LL);
        cout << result;
}

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Do you want an explanation too? :D

Good job! And no need for explanation, I got it by myself, however, when you are learning, it may take you some time :)

I guess the accumulate issue was some time ago Hobson? This is captured by the compiler today.

well the compiler gives a warning now

I got stumped on this one for a while when I first learnt C. :rolleyes:

Code:

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// Oops, infinite loop.
unsigned char c;
for (c = 0; c < 256; c++)
{
        /// Do stuff.
}

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I don't think its an interesting story.

Quote:

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Originally Posted by (V|G)CC4ME

Code:

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# include <iostream>
using namespace std;

int main()
{
  float f[2][2] = {1.0, 2.0, 3.0, 4.0};
  int i = (int)f[1, 1];
  cout << i << endl;
}

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Quote:

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Originally Posted by (V|G)CC4ME

Oh, and as for the answer to my example: I'll leave it unsolved just to see what others think. What would the output be? Why does it compile?

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Without reading other replies ...

1,1 evaluates to 1

f[1] evaluates to the address of the second row, i.e. &f[1][0]

That address is then cast to an int.

Quote:

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Originally Posted by (V|G)CC4ME

What safer coding practice would have prevented this?

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Use static_cast<int> instead of (int).

One of the cutest bug I've seen was something like

Code:

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// check if a is either 3 or 5
if (a == 3 | 5) {

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And some of the cutest code (not a bug, works perfectly) I've seen was this (ok, it's JAVA, not C++):

Code:

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    for(int i=2;i<8;i++){
      if(slotNumber.longValue() == i){
      slotName = "Slot "+ (i-2);
      }
    }

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Both pieces were written by "IT-professionals", not students.

I must say I'm impressed guys. I've made so many bug's in my life I can't pick a favourite... :o

For some reason, I like this one (access violation):

Code:

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#include <iostream>

using namespace std;

char* numbers[10] = {
        "One",
        "Two",
        "Three",
        "Four",
        "Five"
        "Six",
        "Seven",
        "Eight",
        "Nine",
        "Ten"
};

int main()
{
        for (int i = 0; i < 10; ++i)
        {
                        std::cout << numbers[i] << " ";
        }
       
        return 0;
}

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Quote:

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Originally Posted by Zachm

For some reason, I like this one (access violation):

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Admittedly, I am not very familiar with the use of such global variables, but it seems to me that the problems with that example is not an access violation, but a missing semi-colon and that numbers should be an array of const char*.

EDIT:
Ah, the most obvious mistake is now corrected.

Edited my last post.
Didn't try to compile it, but the semi-colon is not the problem I intended to demonstrate.
Disregard the fact that the array is global as well - this was just for demonstration purposes,
and look closer !

hmm... after seeing your correction, I thought that perhaps I miscounted, but you have ten string literals in the array, and the array is of 10 char*, so where's the out of bounds access?

Zachm, your code snippet just killed me. Awesome. I was staring at it trying to find a bug for like 15 minutes, until decided to run it and see. Great example :D

Quote:

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Zachm, your code snippet just killed me. Awesome. I was staring at it trying to find a bug for like 15 minutes, until decided to run it and see.

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I ran it and did not get a seg fault... but I guess I was unlucky.

Yeah, I see the error now, but frankly, it was obscured by other mistakes :p