(referring to an allocation-free strstr if strings had an associated length)
If a string was a (pointer,length) pair, then strstr would return a pair (pointer+offset,length-offset) where, just like in the original strstr, the new pointer points into the existing string. No allocation needed
(But what about the pointer-length pair that has to be created? Well, it will live on the stack just like the return value from the original strstr, which has to be stored somewhere also.)
Except that's not how K&R would have done it. It would have been pascal style: one byte of length directly followed by the string itself in memory. The pointer would be the address of the length byte. Now it's hard to create strstr without copying so they wouldn't. Instead you would have a new API where every call would have offsets to the beginning, likely it would be one based too. Anyway C does it the way it does cause PDP set the zero condition flag on move.
Comments
(referring to an allocation-free strstr if strings had an associated length)
If a string was a (pointer,length) pair, then strstr would return a pair (pointer+offset,length-offset) where, just like in the original strstr, the new pointer points into the existing string. No allocation needed
(But what about the pointer-length pair that has to be created? Well, it will live on the stack just like the return value from the original strstr, which has to be stored somewhere also.)
Except that's not how K&R would have done it. It would have been pascal style: one byte of length directly followed by the string itself in memory. The pointer would be the address of the length byte. Now it's hard to create strstr without copying so they wouldn't. Instead you would have a new API where every call would have offsets to the beginning, likely it would be one based too. Anyway C does it the way it does cause PDP set the zero condition flag on move.