Driver code
public static void main ( String args [ ] ) { String s1 = " for " ; String s2 = " geeksforgeeks " ; int res = isSubstring ( s1 , s2 ) ; if ( res == - 1 ) System . out . println ( " Not ▁ present " ) ; else System . out . println ( " Present ▁ at ▁ index ▁ " + res ) ; } }