Tools

Editors

Emacs and vim are the two standard editors which work via the terminal.

Emacs Shortcuts

Access the Emacs reference card here. Common shortcuts that you will use:

• Ctrl-K: cuts the line
• Ctrl-Y: pastes the line
• Ctrl-Space: starts highlighting, move arrows, then Esc-W to copy.
• Ctrl-X then the number. It opens multiple "buffers", or sub window.
  • Ctrl-X-O jumps between buffers with .
  • Ctrl-X-F to point your buffer to another file. Provide the relative file.
• Ctrl-X-S saves the file.
• Ctrl-X-C quits Emacs.

gdb

gdb is a GNU debugger that allows you to:

• flexibly pause and resume
• print out values of variables mid-stream
• see where severe errrors like Segmentation Faults happen.
• When using gdb or valgrind, compile with -g, which packages up the source code ("debug symbols") along with the executable.

Commands

break main sets a break point (where you want to stop the execution) at the beginning of the main functions. run continues execution. next executes the statement on the current line and moves onto the next and then stops. Use the shortcut n. step begins to execute the statement on the current line. If the statement contains a function call, it steps into the function and pauses there. print <variable-name> prints out the value of the variable. p is the shotcut.

Valgrind

valgrind is a debugging tool for finding memory usage mistakes such as:

• invalid memory accesses: e.g. array index out of bounds
• memory leaks: failure to free dynamically-allocated memory (HEAP SUMMARY).
• invalid read and writes: attempts to dereference pointers to memory that is not yours.

How to use valgrind?

1. Compile program with the flag -g
2. Run the program with valgrind --leak-check=full ./myFile <arg1> <arg2> ...
3. Look for All heap bocks were freed and ERROR SUMMARY: 0 errors for no issues.