Looks good to me, but you can use isalnum(c) instead of isalpha and isdigit.
jopa
2010-05-28 05:56:44
views:
664answers:
4
+8
A:
+1. Also you can use `isspace()` if you want to count other types of whitespace (e.g. tab).
Matt Curtis
2010-05-28 06:03:00
The only suggestion that I have for improvement is to not have `_not_` in function names as it can make for unreadable code. Consider this instead: `return find_if(str.begin(), str.end(), is_alnum_space) != str.end();`
Johnsyweb
2010-05-28 07:20:18
@Johnsyweb: That won't work though. That will return `true` for a string that contains *at least one* alphanumeric+space character, but I want to ensure that they are *all* alphanumeric+space characters. The purpose of the `find_if` is to find the first element that satisfies the predicate, the predicate being "not alphanumeric or space". If we get `str.end()` we know that no character satisfied that predicate, so they must all be alphanumeric or space characters.
dreamlax
2010-05-28 07:33:41
@dreamlax: You are right. It has clearly been a long week :-)
Johnsyweb
2010-05-28 12:25:12
A:
Minor points, but if you want is_not_alnum_space() to be a helper function that is only visible in that particular compilation unit, you should put it in an anonymous namespace instead of making it static:
namespace {
bool is_not_alnum_space(char c)
{
return !(isalpha(c) || isdigit(c) || (c == ' '));
}
}
...etc
Ilkka
2010-05-28 06:04:21
+1
A:
You can also do this with binders so you can drop the helper function. I'd recommend Boost Binders as they are much easier to use then the standard library binders:
bool string_is_valid(const std::string &str)
{
return find_if(str.begin(), str.end(),
!boost::bind(isalnum, _1) || boost::bind(std::not_equal_to<char>, _1, ' ')) == str.end();
}
R Samuel Klatchko
2010-05-28 06:09:13
Wow that is crazy and cool at the same time. Although, I don't what to check for all types of whitespace, I just want to check for the space character itself. Is that still possible with binder?
dreamlax
2010-05-28 06:10:49
@dreamlax - yes, that's possible. I've updated the answer to do that.
R Samuel Klatchko
2010-05-28 06:17:24
+1
A:
And looking forward to C++0x, you'll be able to use lambda functions (you can try this out with gcc 4.5 or VS2010):
bool string_is_valid(const std::string &str)
{
return find_if(str.begin(), str.end(),
[](char c) { return !(isalnum(c) || (c == ' ')); }) == str.end();
}
R Samuel Klatchko
2010-05-28 06:19:53