I learned C on a laptop, while flying around the country for business. Not C++ mind you, but plain old C.
I was able to use it to get out of a lot of tight spaces in the days of client/server with database back-ends. We had a big diversity of systems, from MS-DOS 5.x to Windows 98, and we had to handle them all. To make things worse, the different versions of SYBASE each had their own DLL interface, plus a different one depending on the OS using it. Writing a command line launcher was the best way to go, and that's what we did.
It was also a great way to write a program to test the installation of our software. Using an extremely small Linux kernel, I could boot from a floppy and run connectivity tests from the client machines without having to get network access.