C++ stoi() function and exception handling

You asked yourself, but I'll make up for it.

std::stoi() is a function that converts std:string to int. Therefore, if a string that exceeds the expression range of int is entered, the std::out_of_range exception occurs.

Total int can be expressed from a minimum -2147483648 to a maximum 2147483647. The "129380129831213981" you used for conversion goes beyond the expression range of int, so you must use std:stoll().

The reason why the exception was not received successfully in try~catch is that it was written to receive std::string instead of the type of exception thrown in the catch syntax. Sometimes you make this mistake because you don't know what a throwaway exception is, but you can get most of the exceptions by using std::exception or ....

All exceptions from the C++ standard library inherit std::exception. ... means all exceptions. Therefore, you will get most exceptions if you create as below.

try {
    std::string str = "129380129831213981";
    int conv = std::stoi(str);
} } catch (const std::exception& expn) {
    std::cout << expn.what() << ": Out of integer's range\n";
} } catch (...) {
    std::cout << ": Unknown error\n";
}

Note that Stack unwinding means how the stack is cleared until catch is reached when an exception is thrown. It's not because of Stack unwinding that comes back to the try point, it's the grammatical function of try~catch.