适用于在断点停止之前, 想做一些打印输出
debug.writeline(string message)函数，将我们所关心的信息打印在visual studio ide的output窗口中 debug.assert(bool condition)来让程序停在错误的地方
e.g.:
protected override void onresize(eventargs e
)
{
system
.diagnostics
.debug
.assert(this.width
>200,"width should be larger than 200.");
system
.diagnostics
.debug
.writeline(size
.tostring());
}
