1 secondALPHA should be an invalid input for a duration.

[viboes]

I expect the following input to be an invalid

1 seconde

to fail (in English). But it works without scanning the last 'e'.

It seems that this is the current practice in the standard

But this goes against current practice:

#include <sstream>
#include <iostream>

int main()
{
    std::istringstream in("1e+10");
    int s = 10;
    in >> s;
    if (!in.fail())
        std::cout << s << '\n';
    else
        std::cout << "failed\n";
    char c = 0;
    in >> c;
    if (!in.fail())
        std::cout << c << '\n';
    else
        std::cout << "failed\n";
}

Outputs

1
e

I think, however that this is a different case, as integers and letters could be go together.

I can understand that after

1 second

any non alpha character could be accepted, but not an alphabetic.

The solution could be simple. Once the unit keyword match, a check on the next character (if one) is done to ensure that isalpha(c) is false.

[viboes]

It seems that the standard io works this way (no need to have white space separators, so fixed as invalid.