🚀 go-pugleaf

It seems like this is a decent way of checking:

v = strtol(value, &end, 0 );
if((end-value) != strlen(value))
   // not a valid number


>"Ed Mulroy [TeamB]" <ed@mulroyREMOVETHESECHARS.org> wrote:
>
>>The documentation states that 0 is the return value from strtol when there
>>is an error.
>
>I think the OP realised that: "if the value is actually "0" or if its an
>invalid number?"
>
>>If you look in the source code for strtol you will be able to verify that it
>>also sets the errno variable.
>
>Sadly, although the source code indicates that it does, it doesn't work
>for me either (BCB5 + SP):
>
>  #include <cerrno>
>  #include <iostream>
>
>  int main()
>  {
>    char* endptr = 0;
>    char const* data = "***";
>    long res = strtol(data, &endptr, 10);
>    int i = std::errno;
>    std::cout << res << " " << i << " " << ERANGE;
>  }
>
>  C:\>test
>  0 0 34
>  C:\>
>
>(Temporary used just in case std::cout::operator<<() decided to muck
>around with the value of errno.)
>
>As far as my quick scan indicates, the only circumstance that causes
>errno to be set is an actual overflow, and the return value is unlikely
>to be zero in that case. This is as per the C Standard, and the client
>does need to sanity check the input string, probably scanning from the
>input value to endptr to see if there were any digits in the range,
>something like this:
>
>  if (res == 0)
>  {
>    bool is_valid_number = false;
>    for (char const* p = data; p != endptr && !is_valid_number; ++p)
>      if (std::isdigit(*ptr))
>        is_valid_number = true;
>  }
>
>(Not tested)
>
>Alan Bellingham
>-- 
>alanb@episys.com