If we have character string as large as few Gigabytes( take for example 4 GB), whats the most efficient way to reverse it using c++ from time and space point of view? Basically assume that a function will recieve this string as input parameter and the same function should returned reversed string. Performance/speed is the top criteria here. I undertand generally we can use recursive functions, third party libray api's etc for string reversal but in situations where strings are few GB long, that approach may not work. I searched but didnt find any relevant post in this forum. Any ideas? Thank you.