Safely convert std::string_view to int (like stoi or atoi)

Question

Is there a safe standard way to convert std::string_view to int?

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Since C++11 std::string lets us use stoi

Answer 1

The std::from_chars function does not throw, it only returns a value of type from_chars_result which is basically a struct with two fields:

struct from_chars_result {
    const char* ptr;
    std::errc ec;
};

You should inspect the values of ptr and ec when the function returns:

#include 
#include 
#include 

int main()
{
    int i3;
    std::string_view sv = "abc";
    auto result = std::from_chars(sv.data(), sv.data() + sv.size(), i3);
    if (result.ec == std::errc::invalid_argument) {
        std::cout << "Could not convert.";
    }
}