Is there a function like find_last_of in std but not in string?

Question

I know there is function

string::find_last_of

But I want to process a large chunk of char* data. I don't want to assign the char* to a string.

I know there is a std function

std::find

But it only can find char* on positive sequence. Is there such a way to find in reverse order? If not in std, is there a way in boost?

See [rbegin](https://en.cppreference.com/w/cpp/iterator/rbegin), [rend](https://en.cppreference.com/w/cpp/iterator/rend). — n. m. could be an AI, Oct 31 '18 at 03:47
To be clear, are you searching for a single character or a substring? — chris, Oct 31 '18 at 03:51
@chris, currently, I just need searching for a char, further, I want to search for a substring. — Administrator, Oct 31 '18 at 04:10
@zhang no, they don't. `std::rbegin()` and `std::rend()` are standalone functions, not class methods. They work with any container that implements the the `rbegin()` and `rend()` methods, but they are also specialized for fixed arrays, too — Remy Lebeau, Oct 31 '18 at 05:35

score 3 · Accepted Answer · answered Oct 31 '18 at 04:13

std::find_end()

Searches for the last subsequence of elements [s_first, s_last) in the range [first, last).

For example

#include <algorithm>

char *data = ...;
char *data_end = data + size;
char toFind = ...;
char *pfind = &toFind;

char *found = std::find_end(data, data_end, pfind, pfind + 1);
if (found != data_end)
    ...

score 2 · Answer 2 · edited Oct 31 '18 at 05:39

If you want to search for one character, like std::find() does, you can use... std::find(). Take a look at std::reverse_iterator:

auto foo(char* str, std::size_t size, char to_find)
{
    auto rev_it = std::find(std::make_reverse_iterator(str + size),
                            std::make_reverse_iterator(str),
                            to_find);
    auto it = std::make_reverse_iterator(rev_it);

}

score 1 · Answer 3 · answered Oct 31 '18 at 04:23

1

There is a function in boost can solve this problem.

boost::algorithm::find_last

example:

char* s = "abcdabc";
cout << boost::algorithm::find_last(s, "b").begin() - s;

answered Oct 31 '18 at 04:23

Administrator

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Is there a function like find_last_of in std but not in string?

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