C++: Find matching characters in character array

Question

How do I implement a c++ script to search a group of characters from an character array.The search characters are not case sensitive.For an example, I key in "aBc" and the character array has "abcdef" and it is a hit and shows the found.

This is my script,don't know what is wrong.

#include <iostream>
#include <cstdlib>
#include <cstring>

using namespace std;

int main()
{
  char charArr1[]="abcdefghi";
  char inputArr[20];

  cin>>inputArr;
  charArr1.find("abc");
}

I recevied this error. request for member 'find' in 'charArr1', which is of non-class type 'char [10]

Is there any reason why you don't use `std::string`? This would be a lot easier. — Shafik Yaghmour, Jul 19 '13 at 14:40

score 3 · Answer 1 · edited May 23 '17 at 11:49

3

copy your inputs and convert them to lower case (see How to convert std::string to lower case?)
perform usual search (http://www.cplusplus.com/reference/string/string/find/)

edited May 23 '17 at 11:49

Community

1
1

answered Jul 19 '13 at 14:09

Yulia V

3,507
10
31
64

Sorry for the spam, I am new here. Thanks for the reply! – nubbear Jul 19 '13 at 14:25
The answer in the link you post is incorrect, and invokes undefined behavior (at least on many platforms). You cannot call `::tolower` with a `char`. – James Kanze Jul 19 '13 at 14:35

score 1 · Accepted Answer · answered Jul 19 '13 at 14:41

The easiest solution is to convert the input to lower case, and use std::search:

struct ToLower
{
    bool operator()( char ch ) const
    {
        return ::tolower( static_cast<unsigned char>( ch ) );
    }
};

std::string reference( "abcdefghi" );
std::string toSearch;
std::cin >> toSearch;
std::transform( toSearch.begin(), toSearch.end(), toSearch.begin(), ToLower() );
std::string::iterator results
    = std::search( reference.begin(), reference.end(),
                   toSearch.begin(), toSearch.end() );
if ( results != reference.end() ) {
    //  found
} else {
    //  not found
}

The ToLower class should be in your toolkit; if you do any text processing, you'll use it a lot. You'll notice the type conversion; this is necessary to avoid undefined behavior due to the somewhat special interface of ::tolower. (Depending on the type of text processing you do, you may want to change it to use the ctype facet in std::locale. You'd also avoid the funny cast, but the class itself will have to carry some excess bagage to keep a pointer to the facet, and to keep it alive.)

C++: Find matching characters in character array

2 Answers2