1. What dose it mean?
Hand-tracing is a simulation of code execution in which you step through instructions and track the values of the variables
2. How do you do it?
When you hand-trace code or pseudocode, you write the names of the variables on a sheet of paper, mentally execute each step of the code and update the variables.
It is best to have the code written or printed on a sheet of paper. Use a marker, such as a paper clip, to mark the current line.
Whenever a variable changes, cross out the old value and write the new value below. When a program produces output, also write down the output in another column.
3. Example
原文：https://www.cnblogs.com/JasperZhao/p/12898229.html