What happens to memory after '\0' in a C string?

Question

Surprisingly simple/stupid/basic question, but I have no idea: Suppose I want to return the user of my function a C-string, whose length I do not know at the beginning of th

Answer 1

To elaborate on the use of the NULL terminator in C: You cannot allocate a "C string" you can allocate a char array and store a string in it, but malloc and free just see it as an array of the requested length.

A C string is not a data type but a convention for using a char array where the null character '\0' is treated as the string terminator. This is a way to pass strings around without having to pass a length value as a separate argument. Some other programming languages have explicit string types that store a length along with the character data to allow passing strings in a single parameter.

Functions that document their arguments as "C strings" are passed char arrays but have no way of knowing how big the array is without the null terminator so if it is not there things will go horribly wrong.

You will notice functions that expect char arrays that are not necessarily treated as strings will always require a buffer length parameter to be passed. For example if you want to process char data where a zero byte is a valid value you can't use '\0' as a terminator character.