do you know why this is calling segfault in qt?

[Milan Krejci]

int nejmensi;
for (int i=1;i<pole.size();i++) {
if (pole.at(i)<pole.at(i-1)) nejmensi=i;
}
return nejmensi;

 

[Victor Bazarov]

int nejmensi;
for (int i=1;i<pole.size();i++) {
if (pole.at(i)<pole.at(i-1)) nejmensi=i;
}
return nejmensi;

"Calling segfault"? As in "undefined behaviour"? <shrug> No,
we don't know. What is 'pole'? Read the FAQ 5.8 before you
proceed.

V

 

[Jim Langston]

int nejmensi;
for (int i=1;i<pole.size();i++) {
if (pole.at(i)<pole.at(i-1)) nejmensi=i;
}
return nejmensi;

Could be many reasons, need to see more code.

What happens when pole.size() is 0?

 

[Alf P. Steinbach]

* Milan Krejci:

int nejmensi;
for (int i=1;i<pole.size();i++) {
if (pole.at(i)<pole.at(i-1)) nejmensi=i;
}
return nejmensi;

As Jim Langston remarked else-thread, pole.size() 0 is not covered by
your logic.

In that case you're returning an indeterminate value, which could be
anything.

Most likely that indeterminate value causes the calling code to do
something Bad.

 

[Victor Bazarov]

Could be many reasons, need to see more code.

What happens when pole.size() is 0?

The 'for' loop is not going to be executed. 'nejmensi' is
not initialised. Even returning its value is undefined
behaviour, right?

V

 

[Jim Langston]

The 'for' loop is not going to be executed. 'nejmensi' is
not initialised. Even returning its value is undefined
behaviour, right?

Exactly. And whatever used the value of nejmensi will be using an undefined
value. Which may be whats causing the error, we don't know. Need to see
more code. Need to know the actual line the error is occuring on, etc...

It may be the operator< for whatever is stored in pole. Need to see more
code.