#include <iostream>
 
void compareChar(char *myArr, char *mySecArr);
 
int main()
{	
	char mychar[] = "xabaacbaxabb";
	char letters[2];
 
	compareChar(mychar, letters);
 
	std::cin.ignore(2);
 
	return 0;
}
 
void compareChar(char *myArr, char *mySecArr)
{
	int count = 0;
 
	std::cout << "Enter two letters to be compaired with the char string 'xabaacbaxabb'" << std::endl;
 
	std::cin >> mySecArr;
 
	while(strlen(mySecArr) != 2)
	{
		std::cout << "Wrong amount of letters, try again!" << std::endl;
		std::cin >> mySecArr;
	}
 
	for (int i = 0; myArr[i] != 0; i++)
	{
		if((myArr[i] == mySecArr[0]) && (myArr[i+1] == mySecArr[1]))
			count++;
	}
 
	std::cout << "The pair '" << mySecArr << "' appears " << count << " time(s) in " << myArr << "." << std::endl;
}

// retuns the last position in the string where the match was found
// modifies the count parameter passed by reference which displays the
// number of times substring occurs.
int my_strstr( const char* str1, const char* str2, int* count )
{
    int i = 0 ;
    int len1 = strlen( str1 ) ;
    int len2 = strlen( str2 ) ;
    int pos = 0 ;
 
    *count = 0 ;    // initialize the counter
 
    for( i = 0; i < len1; ++i )
    {
        if( strncmp( ( str1 + i ), str2, len2 ) == 0 )
        {
            (*count)++ ;
            pos = i ;
        }
    }
    return pos ;
}
 
int main( void )
{
    int count ;
    char str[] = "ababababa" ;
    char search_str[] = "ab" ;
    int match = my_strstr( str, search_str, &count ) ;
    printf( "The last occurance of \'%s\' was found in \'%s\' at %d.",
                                                str, search_str, match ) ;
    printf( "\nThe count of \'%s\' is %d.", search_str, count ) ;
    getchar( ) ;
 
    return 0 ;
}

//Exercises from the book: The C++ Programming Language by Bjarne Stroustrup.
 
/*Write a function that counts the number of occurences of a pair of letters in a string and
  another that does the same in a zero-terminated array of char(a C-style string). For example,
  the pair "ab" appears twice in "xabaacbaxabb".
  */
 
#include <iostream>
#include <string>
 
int compareChar(char *myArr, char *mySecArr);
int compareString(std::string myWord, char mySecArr[2]);
 
int main()
{	
	char mychar[] = "xabaacbaxabba";
	char letters[2];
	std::string myWord;
 
	myWord = mychar;
 
	std::cout << "Enter two letters to be compaired with the char string '" << mychar << "'" << std::endl;
 
	std::cin >> letters;
 
	int count = compareChar(mychar, letters);
	std::cout << "The pair '" << letters << "' appears " << count << " time(s) in " << mychar << "." << std::endl;
 
	std::cout << "Enter another two letter to be compaired with the string string '" << myWord << "'" << std::endl;
 
	std::cin >> letters;
 
	count = compareString(myWord, letters);
	std::cout << "The pair '" << letters << "' appears " << count << " time(s) in " << myWord << "." << std::endl;
 
	std::cin.ignore(2);
 
	return 0;
}
 
int compareChar(char *myArr, char *mySecArr)
{
	int count = 0;
 
	for (int i = 0; i < strlen(myArr)-1; i++)
	{
		if((myArr[i] == mySecArr[0]) && (myArr[i+1] == mySecArr[1]))
			count++;
	}
 
	return count;
}
 
int compareString(std::string myWord, char mySecArr[2])
{
	int count = 0;
 
	for (int i = 0; i < myWord.size()-1; i++)
	{
		if ((myWord[i] == mySecArr[0]) && (myWord[i+1] == mySecArr[1]))
			count++;
	}
 
	return count;
}

char letters[2];