Rope data structure

Question

Hi

Is it really a o(n) time complexity for concatenation of one string another string?

str1 = "Hi" and str2 = " Welcome" and now I wanted str1 = Hi Welcome.... How come this take o(n) time ? Is this true or this is true only if we concatenate two data string into thrird?

If so, what's the use of rope data structure? Is direct operation on string is costly?

Answer 1

https://www.geeksforgeeks.org/ropes-data-structure-fast-string-concatenation/