STL count()

This is a discussion on STL count() within the C++ Programming forums, part of the General Programming Boards category; Is there any alternative to count() function of STL, I don't have any problem with it, but just wanna know. ...

  1. #1
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    STL count()

    Is there any alternative to count() function of STL, I don't have any problem with it, but just wanna know.

    And how to do the same thing that count() does? Like check and count the number of times a given value appears in vector?

    One more question can the count() function be used with arrays, or its limited to only STL containers ?

  2. #2
    Registered User hk_mp5kpdw's Avatar
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    Any alternative? Make your own... look at the code in the <algorithm> header file to see how it works. It can be used with an array just as easily as an STL container.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  3. #3
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    Yes, you can use count on an array. I took the example code here:
    http://www.cppreference.com/cppalgorithm/count.html

    Bashed it about a bit to make a program using an array:
    Code:
    #include <iostream>
    #include <algorithm>
    
    using namespace std;
    
    int main()
    {
     int v[10];
     for( int i = 0; i < 10; i++ ) {
       v[i] = i;
     }              
    
     int target_value = 3;
     int num_items = count( &v[0], &v[10], target_value );             
    
     cout << "v contains " << num_items << " items matching " << target_value << endl;     
    };
    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  4. #4
    and the hat of sweating
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    If you're asking if they have 2 functions that do the same thing, then no (why would they?). There's also count_if(), but it works a little differently.

  5. #5
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    By the way, without looking at the implementation of count, I expect it does something similar to this:
    Code:
    template<typename IT, typename T>
    int count(IT begin, IT end, T target)
    {
        int c = 0;
        for(IT i = begin; i != end; i++)
            if (*i == target) c++;
        return c;
    }
    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  6. #6
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    thanks everyone

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