John Graham-Cumming

How I coded in 1985

Back in 1985 I worked on the computerization of a machine designed to stick labels on bottles. The company that made the machines was using...

One line you should add to every makefile

If you're using GNU make and you need help debugging a makefile then there's a single line your should add. And it's so useful that you sho...

Steve Ballmer's incorrect binary search interview question

In this short video Steve Ballmer talks about a puzzle question he would ask candidates interviewing at Microsoft. Solving it is based on b...

Some things I've learnt about programming

I've been programming for over 30 years from machines that seem puny today (Z80 and 6502 based) to the latest kit using languages that rang...

“The GNU Make Book”: probably more than you ever wanted to know about make

So, it's finally here. My second book, entitled The GNU Make Book and published by No Starch Press later this month (electronically it's a...

Things I like about programming in Go

I recently wrote a blog post for CloudFlare about our use of Go . I thought it was worth following up with a bit more detail about why I li...

In praise of... text files and protocols

The other night I had to debug a problem where CMYK colors specified in an OmniGraffle file weren't making it into an exported PDF (or at...

"We've read your code"

Two ways to use an LED as a light sensor with Arduino

I needed to log when a light switched on and off during the night as part of debugging an oddly behaving movement sensor. To do that I built...

Your last name contains invalid characters

My last name is "Graham-Cumming". But here's a typical form response when I enter it: Does the web site have any idea how rude it is to cla...

To boldly go where Node man has gone before

With all the chatter about how uber-amazing Node.js is I figured I'd do a little comparison with my favorite language du jour: Go . Node'...

My primality testing code is faster than Sir Roger Penrose's

But, I guess he did win the Nobel Prize for Physics in 2020 so I can't really brag. However, it was a great surprise when looking at two pa...

Your test suite is trying to tell you something

A few weeks ago I started wondering about 'the test that occasionally and randomly breaks' in a large test suite at my job. The test, calle...

Five bugs in a single line of JavaScript

Today I've been working with a piece of third-party software. I was having big problems getting it working and decided to delve into its ...

UseTheSource: a place for beautiful code

GNU make insanity: finding the value of the -j parameter

The other day at work a colleague posed the seemingly innocent question "Can I find out the value of the GNU make -j parameter inside a Ma...

Breaking the Reddit code

A few days ago an entry on Reddit asked for help breaking a code . Because I was laid up in bed yesterday with something chesty and nasty I...