assert(指针)引发分段违规

Question

在检查指针是否为0时,我遇到了这个烦人的分段错误.这是有问题的代码:

bool egammaMVACalib::checkTree()
{
   // Not a TChain
   cout << "a" << endl;
   assert(m_tree);      // crash on line 751 (this one)
   cout << "B" << endl;

m_tree是一个egammaMVACalib类型的数据成员,TTree*所以我真的不明白为什么assert(m_tree)可以引发分段违规.这是堆栈跟踪的输出

a
19:07:25 30574 Wrk-0.9 | *** Break ***: segmentation violation

===========================================================
There was a crash.
This is the entire stack trace of all threads:
===========================================================
#0  0x000000361869a4d5 in waitpid () from /lib64/libc.so.6
#1  0x000000361863c481 in do_system () from /lib64/libc.so.6
#2  0x00002ac5099cb322 in TUnixSystem::StackTrace() ()
    from /usr/local/proof/root/lib/libCore.so
#3  0x00002ac5099c7fea in TUnixSystem::DispatchSignals(ESignals) ()
    from /usr/local/proof/root/lib/libCore.so
#4  <signal handler called>
#5  egammaMVACalib::checkTree (this=0x0) at ../Root/egammaMVACalib.cxx:751
#6  0x00002ac5117e5563 in egammaMVACalib::LoadVariables (this=0x1, index=0)
    at ../Root/egammaMVACalib.cxx:492

Answer 1

如果你看第5帧,你的this指针就是空的.这意味着问题从那里开始.断言中的段错误仅仅是对它的重新诠释!