Returns a new string that is a substring of the specified string.
The substring begins at the specified beginIndex and extends to the character
at index endIndex-1. Thus the length of the substring is endIndex-beginIndex.
Parameters:
s
beginIndex
endIndex
s.length() is assumed.
You may call this function in a method-like style:
s.substring(beginIndex, endIndex)
"hamburger".substring(4, 8) returns "urge""smiles".substring(1, 5) returns "mile"