Creating new strings by exchanging the first half of a and b .
string c = a . Substring ( 0 , la / 2 ) + b . Substring ( lb / 2 , lb / 2 + 1 ) ; string d = b . Substring ( 0 , lb / 2 ) + a . Substring ( la / 2 , la / 2 ) ; Console . Write ( c + " STRNEWLINE " + d + " STRNEWLINE " ) ; }