Reading Summary 2016-12


How to find size of an array in C without sizeof

The difference between arr and &arr - basically, arr is of type int , and &arr is of type (int )[size].

Very excellent article on the fundamentals of C/C++!

What Every C Programmer Should Know About Undefined Behavior

Some “gotchas” and pitfalls in the C programming language and how sometimes compiler optimizations can make it worse. Long story short is, steer away from undefined behaviors.

This post is from Chris Lattner himeself. Really nice article.


Python Has Big Impact At Red Hat

Why Python is such a cool language and how Python is used in Redhat. Most of redhat’s important infrastructure is written in Python, including but not limited to firewalld, yum, and its successor dnf, and many cloud PaaS tools for OpenShift.

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Reading Summary in 2015/10


Troubles with GCC signed integer overflow optimization

BUG 30475 - assert(int+100>int) optimized away

An interesting ‘bug’ in some versions of GCC (and Clang as well) implementation. Since it’s ‘undefined’ behavior after all, compiler is not obliged to implement it as a defined behavior. Use -fwrapv flag in GCC to inform the compiler that integer value wraps.


Profiling Python in Production

Signal timeout for every small amount of time (say, 1ms in this case) and record the current stack, and we can infer time spent in each function precisely enough. A smart way of profiling large Python programs.

Note: python signal callback passes signal type and signal handler, and signal handler takes signal number and current stack frame.

Hitchhiker’s Guide to Python

Great book to Python, covering code style, best practices and scenario guide. Just started reading it.