54 replies to this topic

[HappyCoder]

for (i = 0; i < foo; ++i)
{
     for (j = 0; j < bar; ++i)
     {

     }
}

Luckly I have done this enough that I have gotten pretty good at finding it.

[Sik_the_hedgehog]

Just wrote this. Luckily it got caught as a warning, otherwise it'd have been really annoying. Just so you know, name is a const char*.

for (unsigned len = 0; *name; len++, *name++) {

Why is ++ allowed on a const value? I'd like to say that maybe it's because the return value is modified, but it's a post-increment (so the original value would be returned) and even then there are other easy ways to approach that (e.g. the + operator). Take into account this is C, not C++, so there isn't any wacky overloading going on (and even then, it's a char...). Moreover, it's being compiled with -std=c99, so extensions are disabled.

(and before you ask, no, I wasn't reinventing strlen, the loop code does more than just counting characters)

[MaulingMonkey]

*name++ is *(name++), not (*name)++

[Sik_the_hedgehog]

MaulingMonkey, on 26 February 2012 - 04:28 AM, said:

*name++ is *(name++), not (*name)++

Derp, and the most ironic is that I had remembered that syntax specifically (since it matches one of 68000's addressing modes). I wonder what was I thinking when I wrote that post.

[JavierMC]

uint16 numVerts = 0;
for(size_t i = 0; i<70000; i++)
	numVerts++;

Twice last week

[MaulingMonkey]

Here's another really fun one:

for ( size_t i = 0 ; i < v.size() - 1 ; ++i )
{
	...
}

[Telastyn]

C#: I was hunting down a bug, so went in and set a conditional breakpoint deep in the bowels of this data access code

entity.Location = "http://....somebiglongstring.html"

And then went to lunch. Came back and bug was still there, but the breakpoint wasn't hit. Rebuilt, redeployed and still a bug. Nobody else got the bug though, and it worked fine in release mode. Step throught the code... data model entity goes into the translator, view model comes out with the wrong location...

Took me 2 days to find the conditional breakpoint which will do the assignment, and will never actually trigger since assignment isn't "true".

[Alpha_ProgDes]

JavierMC, on 28 February 2012 - 04:09 AM, said:

uint16 numVerts = 0;
for(size_t i = 0; i<70000; i++)
	numVerts++;

Twice last week

MaulingMonkey, on 28 February 2012 - 10:43 AM, said:

Here's another really fun one:

for ( size_t i = 0 ; i < v.size() - 1 ; ++i )
{
	...
}

I acknowledge I'm a bad C++ programmer, but what exactly was the problem with those pieces of code. They both will compile and run. Won't they?

[swiftcoder]

Alpha_ProgDes, on 28 February 2012 - 12:23 PM, said:

I acknowledge I'm a bad C++ programmer, but what exactly was the problem with those pieces of code. They both will compile and run. Won't they?

The first one is just a waste of time - he might as well have set numVerts directly.

The second will fail horribly if v.size() == 0.

[way2lazy2care]

swiftcoder, on 28 February 2012 - 12:28 PM, said:

The second will fail horribly if v.size() == 0.

Why would it fail? Wouldn't it just do nothing? Or is it because v.size()-1 presumably is unsigned since it's being compared against a size_t so it would run MAX_INT times?

[swiftcoder]

way2lazy2care, on 28 February 2012 - 12:38 PM, said:

Why would it fail? Wouldn't it just do nothing? Or is it because v.size()-1 presumably is unsigned since it's being compared against a size_t so it would run MAX_INT times?

Because size() returns a size_t, which is unsigned. And (unsigned)-1 is a very, very large number...

[alnite]

The first one is an uint16, which presumably, a 16-bit integer whose maximum value is 65536. That loop iterates 70000 times.

The second one is the conditional

i < size()-1

. The last element won't get counted for. And of course, if size() returns 0, it will evaluate to a very large number.

[Luckless]

How is this for a brain dead mostly asleep error?

Trying to work on something while way past too tired to program, but I needed to get something done that I could actually show someone.

started with

for x in a:
    for y in a:
	   # Do something with x[0] ... y[1]
#A short time later...
for x in a:
    #Do something else x[0] .... y[1]

Also managed to screw myself over trying to hunt down a bug over position 1 vs 0 of a list. Translating some notes written by someone else into code can be dangerous. The issue was so hard to track because for most of the data set had the same value in the first two elements of the list, except for a few rare cases.

[markadrake]

if(x % 1 === 0)

I did this a few nights back, I was up really late playign around with JavaScript and the Canvas HTML Element and for some reason needed to test if something was odd or even...

This is obviously not how you do it.

[Bacterius]

function Vector(const X, Y, Z: Double): TVector;
begin
 Result := Vector(X, Y, Z);
end;

It just seemed logical at the time I wrote this