quartz/content/notes/debugging.md

title
Debugging

Debugging

removing technical faults isolaing and remove technical faults a human process

• requires creativity/disipline/knowledge
• deepr understanding of code

debuggers are tools to help debugging

1 common approaches

temporarily add output of diagnostic info

• "printf" debugging permanently include calls to logging system
• route to terminal, log files etc

2 debugging machine code

• cpu runs code instruction by instruction
  • thus debugger can intervene between instructions
  • most cpus help debugger interrupt and resume programs
• cpu reached current code via a sequence on callers
  • called stack trace , aka back frame, stack frame etc
• may reach point where it cannot continue
  • e.g., integer division by zero, program execution must stop
  • stack trace of stopped program can be analysed

3 Imperative languages

These are language that are executed in a step-wise, sequentail manner.

• debug symbols
  • e.g., method named, variable named
• source code context
  • line numbers
  • variable name
  • function method names

4 doing debugging

4.1 stepping skipping running

• step into --> steps one statement and steps into function calls
• step over --> a step that treats function calls as statement
• step out --> return to the instruction after the function call you're in
• continue --> go back to running code continuously

4.2 controlling debugger execution

Can run normally --> debugger wil run when program crashes Set Breakpoint --> debugger will stop program when/if that line is reached - conditional breakpoints only suspend if a condition is true Watch point --> program is suspended when some data changes (e.g., variables)

5 debugging non imperative languages

e.g, spreadsheet (Dataflow programming)

• no breakpoints
• must step through iterations of computations

e.g., Equation

• break into smaller parts
• try 'compile' it in multiple ways

e.g., Data base query (declarative programming)

• -reexpressign the query and comaring can be useful