Vicente Botet wrote: I'm looking for a use case where the use of swap_in_place (or whatever is renamed) is not followed/preceded by a copy. When I need to send a message I need to copy the information to send in a buffer. I gues that in this case the use of swap (copy) is the function to use. Can somene help me to identify a real use case on which the swap_in_place can be used to send a message that do not need to be initialized before sending? When I receive a message, I will need to store some of the messages information on application context, store them on local variables or pass them to other functions. All this suppose a copy from the buffer to the different kinds of native storage. I gues that swap (copy) should be used in this case also. The example of Terry reveives a array of ints and makes a swap_in_place, but do nothing with. Someone has proposed to sum all these ints, but in this case, we don't need to swap_in_place and the count. With swap approach, we can count at the same time as we do the conversion, so no need to swap in place. Can somene help me to identify a real use case on which the swap_in_place can be used to reveive a message, without needing to do any additional copy from the swapped buffer to native data? Terry replied: Yes. Image/video decompression. In these cases, each video frame is stored on a physical medium or is sent streaming across a network. The image is usually represented as a matrix of "coefficients" that are in either big- or little-endian format. During the decompression, the coefficients may be read several times, so it is beneficial to store these coefficients in native format in memory. Doing computation in place and transforming data is also quite common in signal-processing, e.g. the Fourier transform. Doing computation in place also provide a performance advantage because of memory caching. That said though, such high-performance applications usually involve (for me) exploitation of the underlying hardware and processor instruction set for the performance critical parts, and therefore, don't fall in the realm of generic C++ implementation. But... these applications usually also eventually involve some form or error-correction and/or compression close the the communication/storage layer. Once that happens, then the data is necessarily copied to another format. Frequently, these operations access blocks of the input stream and cannot be done in place (an in-place decompression algorithm doesn't make much sense). Once you need to do the copy, the advantage of in-place-conversion is lost. terry