alt Hacker News if (sscanf(string,"%lf",&foo) != 1)
{
bad_float();
}
For extra reassurance, initialize foo to NaN or DBL_MAX or something, and verify that it is no longer equal to that value.
Replies
rwmj • today at 10:03 AM
Annoyingly this doesn't detect certain errors. This is one thing I'd like to change in the next C standard, but (from discussions I had with someone who works in those standards) they don't want to break existing code. Which seems like a very bogus justification to me as that code is broken already.
Also the locale thing could be solved by adding another %-directive to say "this format string should be treated in the C locale", like %C (if it's not already used).
IOW this could be made to work, but human factors prevent it.
➕ show 1 reply
shakna • today at 5:28 AM
sscanf has locale things that make it include implementation-defined behaviour, doesn't it?
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That doesn't detect overflows and underflows. Also changes based on locale, which is not thread safe (so you cannot set locale, convert, then unset locale).