why i need to put backslash??

Answer 1

where?
useuly we need it for given another meening to character that is not the regular use of it. the backslash tell the program to use the second meen2

Answer 2

ooooh i see

Answer 3

backslashes are for "escape characters". These are explained in 3rd part of "Strings".

Answer 4

for escape characters we use backslash