Re: "undefined behavior"?

Am 12.06.2024 um 22:47 schrieb DFS:

Wrote a C program to mimic the stats shown on:
 https://www.calculatorsoup.com/calculators/statistics/descriptivestatistics.php
 My code compiles and works fine - every stat matches - except for one anomaly: when using a dataset of consecutive numbers 1 to N, all values  > 40 are flagged as outliers.  Up to 40, no problem.  Random numbers dataset of any size: no problem.
 And values 41+ definitely don't meet the conditions for outliers (using the IQR * 1.5 rule).
 Very strange.
 Edit: I just noticed I didn't initialize a char:
before: char outliers[100];
after : char outliers[100] = "";
 And the problem went away.  Reset it to before and problem came back.
 Makes no sense.  What could cause the program to go FUBAR at data point 41+ only when the dataset is consecutive numbers?
 Also, why doesn't gcc just do you a solid and initialize to "" for you?
 

Maybe it's because you've too many uninitialized data which doesn't
touch the stack's guard page and the initialized variables are beyond
that and not in the guard page in the uninitialized area of the stack.