> Imagine you are writing performance sensitive code. You want to get a substring from a string, one that is not going to live outside your hot loop. In standard C you can just reference a part of a string with a pointer offset.
If you want your substring to terminate in the same place as the original, at a null terminator. But that sadly is almost never the case, and as many C practitioners know, references like this are often unsafe and so APIs that substring tend to copy. That's just what they have to do to pass address sanitizer and static analysis checks.
If you want arbitrary views on a null terminated string, well, it's no longer null terminated and that's just the start of your problems in C.
In languages like Rust and Go, taking a view of a string or array is safe and doesn't copy the underlying data or require an allocation. So if you are writing performance sensitive code where substrings are a major contributor to CPU cycles, best go with those language (or C++) rather than C.
That’s fair: you won’t be able to use any libc functions that rely on null termination. But a lot of the time you don’t need to either. Think writing the substring to a socket or comparing it to a known constant.
In Rust, you would do both of those with a &str, which works fine. Just works exactly as in C, with no calls to memcopy or allocator or anything. And you would also be able to do all the other things that in C use null termination, too.
If you want your substring to terminate in the same place as the original, at a null terminator. But that sadly is almost never the case, and as many C practitioners know, references like this are often unsafe and so APIs that substring tend to copy. That's just what they have to do to pass address sanitizer and static analysis checks.
If you want arbitrary views on a null terminated string, well, it's no longer null terminated and that's just the start of your problems in C.
In languages like Rust and Go, taking a view of a string or array is safe and doesn't copy the underlying data or require an allocation. So if you are writing performance sensitive code where substrings are a major contributor to CPU cycles, best go with those language (or C++) rather than C.