What is the difference between SIGABRT and SIGSEGV

I made the core dumped error with the two pieces of codes below:

//test.cpp
int main()
{
int *p = new int;
*p = 100;
delete p;
delete p;
return 0;
}

//test2.cpp
int main()
{
int *p = new int;
*p = 100;
delete p;
*p = 111;
std::cout<<*p<<std::endl;
return 0;
}

Gdb told me that the first piece of code got core dumped because of the signal SIGABRT, whereas the second piece of code got core dumped because of the signal SIGSEGV.

Could you tell what is the difference?

Deleting a pointer twice is undefined behavior, which means anything can happen. In this case, it results in the `SIGABRT` signal being issued.

Accessing memory which does not belong to the program is also undefined behavior which in this case results in segmentation fault and `SIGSEGV` is issued.


- `SIGABRT` indicates an error detected by the program itself and reported by calling [`abort`][1].
- `SIGSEGV` indicates an invalid access to valid memory.


[1]:

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The SIGABRT is **explicitly detected and signaled** by the implementation of _delete_ whose detected the invalidity of the second delete. It is launch by calling the _abort_ function

The SIGSEGV is different, it is **undergoing** rather than detected by a check in a library like the previous, it is launch through the memory management of the OS

see

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Both of these examples are *undefined behaviour*, this means according to c++ the compiler (and system) can do whatever it wants.

- In case 1, there is likely a check for the double delete of a pointer, therefore `SIGABRT` is signaled. `SIGABRT` means *abnormal termination condition, as is e.g. initiated by abort()*.
- In case 2, the system detects your deference of a deleted pointer and
creates a `SIGSEGV` signal. `SIGSEGV` means *invalid memory access (segmentation fault)*

But both are still UB, so this is just a feature of your current compiler/os/system. The difference between the errors is clear from the definition of the errors [here][1]. One is an abort, usually generated by the compiler or coder. One is caused by invalid memory access, usually signaled by the operating system or hardware.


[1]:

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