Binary search for insert char string. Where is the bug? - c++

Question

I have array of strings. I must find one char string in array of strings by binary search algoritm. If there is this one string then function must return position and return true otherwise this function must return position for insert string in array and false.
I have somewhere bug, but I dont know where ((
Example:
bool Binary_search ( char * arr_strings[], int & position, const char * search_string )
{
int start = 0 ;
int end = 10 - 1; // arr_strings [10]
int for_compare;
int middle;
while ( start <= end )
{
middle = ( start + end ) / 2;
for_compare = strcmp ( arr_strings[middle], search_string );
if ( for_compare > 0 )
{
start = middle + 1;
}
else if ( for_compare < 0 )
{
end = middle - 1;
}
else
{
// if search_string is found in array, then function return position in array of strings and return true
position = middle;
return true;
}
}
// if search_string is not found in array, then function must return position for insert string and return false
position = middle;
return false;
}

Answer 1

I think maybe it should be:
if ( for_compare > 0 )
{
end = middle - 1;
}
else if ( for_compare < 0 )
{
start = middle + 1;
}

Answer 2

The issue is that your insertion position is not right.
You should do something like the following:
bool Binary_search ( char * arr_strings[], const char * search_string )
{ //^^^you are not doing recursive, so you don't need position as parameter
int start = 0 ;
int end = 10 - 1; // arr_strings [10]
int for_compare;
int middle;
int position = -1;
while ( start <= end )
{
middle = ( start + end ) / 2;
for_compare = strcmp ( arr_strings[middle], search_string );
if ( for_compare > 0 )
{ //^^^here should switch the order
end = middle - 1;
}
else if ( for_compare < 0 )
{
start = middle + 1;
}
else
{
position = middle;
return true;
}
}
if (position == -1)
{
if(strcmp(arr_strings[middle],search_string) <0 )
{
position = middle + 1;
}else
{
position = middle;
}
}
return position;
}