How to sum repeated consecutive characters in a string?

[xcindiix]

Hi all, im new to C++ programming. Im really confused with the logic behind this question.

The problem is for an inputted string for instance: "YYNNYYYNYNYY"
i need to calculate the total 'Y's in the string, but for every repeated 'Y' add them consecutively.

so its will become --> 1 + 2 + 0 + 0 + 1 + 2 + 3 + 0 + 1 + 2 = 13

im sorry if the explanation is bad.

how would you format it? i was thinking maybe use s.find() to find the position of Y and then test if the next character in the string is also Y. then add 1 to it but then im really confused in how to link everything together.

or do i have to go through the string one by one by using getchar().

im not sure if you would use arrays, but i havent learnt that yet so thats not allows to be used :/

[JLBorges]

> or do i have to go through the string one by one

Yes.

> by using getchar().

No. Use either a range based for loop or (archaic compiler) iterate using the [] operator.

#include <string>
#include <iostream>

int main()
{
    const std::string str = "YYNNYYYNYNYY" ;
    int total = 0 ;

    int increment = 0 ;

    for( char c : str ) // for each character in the string
    {
        if( c == 'Y' ) // if it is a 'Y'
            total += ++increment ; // add one plus the previous increment

        else // it is not a 'Y'
            increment = 0 ; // reset increment
    }

    std::cout << total << '\n' ;

}

[xcindiix]

Thank You Soooo much JLBorgues !!

i tried something else making use of position ... but it doesnt work...

i was just wondering do you think it is feasible .. if not i'll just abandon it >_<

[JLBorges]

> i was just wondering do you think it is feasible

Of course, it is feasible.

a. The first increment has to be by one (not by the position)
b. std::string::find() finds the next occurrence; so you need to look ahead (not behind).
b. The look ahead has to be in a loop; the character may repeat many times.

#include <string>
#include <iostream>

int main()
{
    const std::string str = "YYNNYNNYYY" ;
    const char Y = 'Y' ;
    int total = 0 ;

    for( auto pos = str.find(Y) ; pos != std::string::npos ; pos = str.find( Y, pos ) )
    {

        for( int increment = 1 ; pos < str.size() && str[pos] == 'Y' ; ++pos, ++increment )
            total += increment ;
    }

    std::cout << total << '\n' ;
}