Using GDB (GNU Debugger)

cond n [expression]

This is basically to set breakpoints if you want to only stop when a certain condition is met.

break foo if i == 4

next (n) - steps one line of code, stepping over functions

step (s) - steps one line of code, stepping into functions

print <expression> prints any C expression.

Using LLDB (Low-Level Debugger)

If you’re on an ARM Mac, (any M-series), you’ll need to use LLDB to debug C and C++ code.