try this:
#include <iostream>
#include <cstring>
#include <iostream>
#include <string>
#include <string.h>
using namespace std;
int main()
{
char inputString[11];
int b_in_string, b_occurrence, repetitions, startIndex, endIndex, actual_needed_count;
cout<<"Input string: ";
cin>>inputString;
cout<<"Repetitions: ";
cin>>repetitions;
cout<<"Start index: ";
cin>>startIndex;
cout<<"End index: ";
cin>>endIndex;
if(endIndex < startIndex)
{
cout<<"End index must be larger than start index. Program terminated.";
return 1;
}
b_in_string = 0;
b_occurrence = 0;
for(int i = 0; i < sizeof(inputString); i++)
{
if(inputString[i] == 'b')
{
b_in_string++;
}
}
actual_needed_count = endIndex - startIndex + 1; //start and end indexes inclusive
b_occurrence = b_in_string * actual_needed_count;
cout<<"Number of times 'b' occurs: ";
cout<<b_occurrence;
return 0;
}
It works on https://www.onlinegdb.com/online_c++_compiler. Hope it helps.