To find partial string match in map

Question

I have a map test and its initialize to below

test["auto works"] = 1; test["before word"] = 2; test["before list"] = 3; test["before pattern"] = 4; test["before me"] = 5; test["before hen"] = 6; test["has float"] = 7;

And i have a string search which is initialized to "before me grep lot".

Now i want to find the search string in test map. Ideally i want look a better match for search string "before me grep lot" in test map.

The output should be 5.

please help me out.

Do you want to return all the keys that begin with the search string? — Galik
– Galik, Commented Jun 20, 2015 at 11:40

Kerrek SB · Accepted Answer · 2015-06-20 11:26:36Z

1

Use test.lower_bound(search) (documentation).

answered Jun 20, 2015 at 11:26

Kerrek SB

481k96 gold badges904 silver badges1.1k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Vlad from Moscow · Accepted Answer · 2015-06-20 12:41:22Z

Try the following approach

#include <iostream> #include <string> #include <map> #include <algorithm> #include <iterator> int main() { std::map<std::string, int> test; test["auto works"] = 1; test["before word"] = 2; test["before list"] = 3; test["before pattern"] = 4; test["before me"] = 5; test["before hen"] = 6; test["has float"] = 7; std::string s( "before me grep lot" ); auto it = test.lower_bound( s ); size_t prev = 0, next = 0; if ( it != test.begin() ) { auto pos = std::mismatch( s.begin(), s.end(), std::prev( it )->first.begin(), std::prev( it )->first.end() ); prev = std::distance( s.begin(), pos.first ); } if ( it != test.end() ) { auto pos = std::mismatch( s.begin(), s.end(), it->first.begin(), it->first.end() ); prev = std::distance( s.begin(), pos.first ); } std::string target = prev < next ? it->first : std::prev( it )->first; std::cout << "The closest item is test[\"" << target << "\"] = " << test[target] << std::endl; }

The program output is

The closest item is test["before me"] = 5

If your compiler standard library does not support algorithm std::mismatch with four parameters then the if statements can look like

if ( it != test.begin() ) { std::cout << std::prev( it )->first << std::endl; std::string::size_type n = std::min( s.size(), std::prev( it )->first.size() ); auto pos = std::mismatch( s.begin(), std::next( s.begin(), n ), std::prev( it )->first.begin() ); prev = std::distance( s.begin(), pos.first ); } if ( it != test.end() ) { std::cout << it->first << std::endl; std::string::size_type n = std::min( s.size(), std::prev( it )->first.size() ); auto pos = std::mismatch( s.begin(), std::next( s.begin(), n ), it->first.begin() ); prev = std::distance( s.begin(), pos.first ); }

sample.cpp(165): error C2064: term does not evaluate to a function taking 1 arguments sample.cpp(165): error C2227: left of '->first' must point to class/struct/union/generic type sample.cpp(165): error C2228: left of '.begin' must have class/struct/union sample.cpp(166): error C2064: term does not evaluate to a function taking 1 arguments 1>sample.cpp(166): error C2227: left of '->first' must point to class/struct/union/generic type sample.cpp(166): error C2228: left of '.end' must have class/struct/union std::mismatch(_InIt1,_InIt1,_InTy (&)[_InSize])' : expects 3 arguments - 4 provided
@S Sriniamul It seems that you have an old llibrary that does not support algorithm std::mismatch with four parameters. Wait a minute I will show how to use the old algorithm.

Collectives™ on Stack Overflow

To find partial string match in map

2 Answers 2

Comments

3 Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Related