Is it possible to remove spaces at the beginning and end of a string without creating a new array?

Question

C++ / C#

That is, we have, say, 5 bytes. The first two and the last one are spaces, the rest are characters. Is it possible to free the memory that the spaces have occupied and leave only the memory for characters?

char* str = "  ab ";
// some code 
// str == "ab"

that is, we do not touch ab in any way (they have the same address), we only free the memory where the spaces lie

Answer 1

A string literal " ab "is in a special data segment that (if the processor and OS allows) is read-only. And the memory of the data segment cannot be freed and made a "heap".
If we assume that the text " ab "is in the "heap" - this same heap is a complex data structure and memory is allocated with alignment. Therefore, the realloc function may (but is not required to) give up the end or attach memory to the end. It will be more difficult to give a start, and no library of functions known to me is capable of this.
In addition, C++ came up with the string_view object exactly for this purpose - to pass strings to a function, abstracting from memory allocation and even from trailing null. That's why string_view doesn't have c_str() function.
Of course you can do something like

char* str2 = str + 2;
str2[2] = '\0';
// А str оставь, уничтожать как-то придётся

Of course, if str is on the heap. The segment with literals, I remind you, is read-only, and in an OS like DOS, where you can change, such a replacement can cause bad side effects.

Answer 2

It is impossible to free memory, especially since with such an announcement, memory allocation occurs on the heap. You can trim the string - initial spaces are cut off simply by rearranging the pointer, trailing spaces by rearranging the '\0' character.