A route planner that plots path between two points on a map using real map data from the OpenStreetMap project.
The OpenStreetMap project is an open source, collaborative endeavor to create free, user-generated maps of every part of the world.
gcc [other flags] -g <source files> -o <output file>
-Wall 打印所有警告
-Werror 将所有敬告视为错误
-ansi 只支持ANSI标准的C语法
-pedantic-errors 将所有不符合ISO标准的警告视为错误
run
backtrace: produces a stack trace of the function calls that lead to a seg fault
x <address>: examine, get the value of an address
break <func or file.xx:line>: set break point
condition 1 <condition>: 设置第一个断点触发的条件
step：单步调试
next: 单行调试，不会跳到function 里面去
print
watch my_var: whenever my_var's value is modified，interrupt and print old&new value
finitsh: runs until the current function is finished
info b: display breakpoints
delete: deletes a specified breakpoint
quit