How is rosparam calculating the of leading-zero integers?

Question

Could someone explain how ROS's rosparam command converts input and output values?
Specifically, I am surprised by the following set of commands caused by leading zeros:

$ rosparam set mytest 00111
$ rosparam get mytest
73

This isn't the conversion from binary, so what is happening here?

Answer 1

This is actually a bash feature, which ROS inherits when using the command-line interface. From the arithmetic evaluation section of the bash manual:

Constants with a leading 0 are interpreted as octal numbers.

You could reproduce this behavior without involving ROS at all:

$ echo $((00111))
73 #  73 = 64 + 8 + 1

If you want to convert your number to decimal instead of octal, strip the leading zeroes before converting your value to an integer (see this SO answer )

$ echo $((10#00111))
111