Tips of debuggers

Clang && lldb #

听说clang+lldb >= gcc + gdb, 所以一试:

lldb基本命令 #

与GDB相同

  • break (b) - 设置断点，也就是程序暂停的地方
  • run (r) - 启动目标程序，如果遇到断点则暂停
  • step (s) - 进入下一条指令中的函数内部
  • backtrace (bt) - 显示当前的有效函数
  • frame (f) - 默认显示当前栈的内容，可以通过 frame arg 进入特定的 frame（用作输出本地变量）
  • next (n) - 运行当前箭头指向行
  • continue (c) - 继续运行程序直到遇到断点。
clang hello.c -g -o hello
lldb hello

# lldb
b main
run
n
p str

还有颜色 😂 可视效果确实提高了不少 而且这四个工具可以混用,也蛮好.

GDB #

gdb

First and foremost, you will need to compile your program with the flag “-g” (for debug) to run it via GDB. From there the syntax to start debugging is:

$ gdb -tui [executable's name]

placing breakpoints

break [line number]     or   b [line number]

or [file name]:[line number]
or [function name]

And even better, can set conditional breakpoints:

break [line number] if [condition]

For example, can set (if have a loop)

break 11 if i > 97

Place a “watchpoint” which will pause the program if a variable is modified:

watch [variable]

Once our breakpoints are set, we can run the program with the “run” command, or simply:

r [command line arguments if your program takes some]

How we got to that point:

bt

Display all the local variables and their current values.

info locals

Of course:

p [variable]       ptype [variable]

step 

next

delete [line number]

continue

quit

Playing with fire. As well do it all the way:

set var [variable] = [new value]