Pointer problem

lxy0628

char * s1, * s2, * p;
* (p-s1 + s2) can be compiled and passed
But * (s2 + p-s1) does not compile, why?

珈蓝易拉罐

The two pointers are subtracted to get an integer. The integer can be added to the pointer, but the two pointers cannot be added.

珈蓝易拉罐

In addition, the priority of "+" and "-" are the same, and they are all left-associated, so for the expressions in those two brackets, the compiler tries to understand from the left to the right. Report an error.

diamond52

And it must be a pointer to an array to perform pointer arithmetic

diamond52

Are two pointers to the same array, so it makes sense to perform calculations between the pointers,
The behavior of pointer arithmetic between two pointers is undefined
Grammatically, it is "possible", but logically it is "undefined", which means that the calculation result is meaningless, which is more accurate.

julines

Not too boring, adding two pointers is meaningless.

superandy

Pay attention to the error prompts given by the compiler.