how I can debug this with gdb?

[rolo]

Im trying to do a recursive algoritm and debug it. My problem is that I got
segfault if I run it withous optimizing it with the compiler, since I want
to debug it. If I use a smaller number it runs ok, but im interested on
bigger numbers.

Can anyone help me out and explain why this happens?
heres a sample code: (it doesn't matter if I use template or not, I got the
same results)

If I optimize it with -O3 or -O2 the program runs fine and returns the
expected 0.

#include <iostream>

using namespace std;

template <class T>
inline T one_less(T tmp){
if(tmp > 0) return one_less(tmp - 1);
else return 0;
}//one_less(T tmp){

int main(void){
unsigned long int tmp = 100000;
cout << one_less(tmp) << endl;
cin.get();
return 0;
}//main(void){


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[Artie Gold]

rolo wrote:

Im trying to do a recursive algoritm and debug it. My problem is that I got
segfault if I run it withous optimizing it with the compiler, since I want
to debug it. If I use a smaller number it runs ok, but im interested on
bigger numbers.
Indeed.
Can anyone help me out and explain why this happens?
heres a sample code: (it doesn't matter if I use template or not, I got the
same results)
Sure. Consider the code below. How many recursive invocations of
`one_less' are there going to be?

You're likely `blowing your stack' (hitting an OS limitation).
If I optimize it with -O3 or -O2 the program runs fine and returns the
expected 0.
<OT>
Your compiler (in optimizing mode) evidently performs an optimization
called `tail-call elimination' which replaces a certain class of
recursive calls by a simple loop. I would advise you to search the web
for more details.
</OT>
#include <iostream>

using namespace std;

template <class T>
inline T one_less(T tmp){
if(tmp > 0) return one_less(tmp - 1);
else return 0;
}//one_less(T tmp){

int main(void){
unsigned long int tmp = 100000;
cout << one_less(tmp) << endl;
cin.get();
return 0;
}//main(void){

HTH,
--ag
--
Artie Gold -- Austin, Texas