c++ null pointer 导致segment fault

最新推荐文章于 2024-08-05 21:31:54 发布

原创最新推荐文章于 2024-08-05 21:31:54 发布 · 705 阅读

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本文详细解析了C++中如何通过信号处理机制来应对段错误（如段错误、空指针异常等），特别是针对无法通过传统的异常捕获机制解决的问题进行深入探讨。介绍了使用信号处理函数和特定的信号处理策略来优雅地处理此类问题，并提供了实际代码示例。

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不像java可以catch NullPointerException。

#include <iostream>
#include <exception>
#include <signal.h>
#include <string.h>

using namespace std;
class A {
  public:
  A() : pa(NULL), inta(-1) {}
  A* getPa() { return pa; }
  void fun() { cout << "fun" << endl; }
  int getInta() const { return inta; }
  private:
  A* pa;
  int inta;
};
ostream& operator << (ostream& out, const A& a) {
  return out << "inta: " << a.getInta() << endl;
}

int main() {
  A a;
  A* pa = a.getPa();
  if(pa == NULL) {
    cout << "is null" << endl;
  }
  cout << "pa->fun()" << endl;
  pa->fun();
  cout << "pa" << endl;
  cout << pa << endl;
  cout << "*pa" << endl;

  // segment fault, try catch does not help.
  // catch or ignore SIGSEGV also does not help,
  // because after ignored or catched the signal,
  // the defending operation will be fired again.
  // ie., the cout << *pa << endl; will be executed again.
  cout << *pa << endl;
  cout << "here" << endl;
    
}