Why I am getting this error on input 1534236469 in the below code?

terminate called after throwing an instance of 'std::out_of_range' what(): stoi

int reverse(int x) {
    string s = to_string(x);
    for (int i = 0; i < s.size() / 2; i  ) {
        swap(s[i], s[s.size() - 1 - i]);
    }
    if (x < 0) {
        x = -stoi(s);
    } else {
        x = stoi(s);
    }
    return x;
}

CodePudding user response：

When you reverse 1534236469 you get 9646324351, that does not fit an int, the max value for an int in most cases is 2147483647.

Use stoll instead and use long long instead of int for x, otherwise the assignment will overflow and cause undefined behavior.

CodePudding user response：

You've got two questions: why is terminate() being called, and why is out_of_range() being thrown?

terminate() is being called, per the standard, because you don't have an exception handler (you didn't surround your call to reverse with try...catch).

out_of_range() is being thrown by stoi because the value it's given is out of range for an int. 9646324351, as @anastaciu points out, is outside the range of an int on your machine.