[ C/C++ 常見問題 ] Check whether an integer overflow occurs at runtime?

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Question:
Is there any easy way to check whether an integer overflow occurs at runtime?

Answer:
This is compiler-specific, but if you're using gcc/g++ then you can compile with -ftrapv to issue SIGABRT when signed integral overflow occurs.
Below is the sample code:
- Test.cpp

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1. /* compile with gcc -ftrapv */  
2. #include   
3. #include   
4. #include   
5.   
6. void signalHandler(int sig) {  
7.   printf("Overflow detected\n");  
8. }  
9.   
10. int main() {  
11.   signal(SIGABRT, &signalHandler);  
12.   
13.   int largeInt = INT_MAX;  
14.   int normalInt = 42;  
15.   int overflowInt = largeInt + normalInt;  /* should cause overflow */  
16.   
17.   /* if compiling with -ftrapv, we shouldn't get here */  
18.   return 0;  
19. }  

Compile and execute:

$ g++ -ftrapv Test.cpp
$ ./a.out
Overflow detected
已經終止