c++ - Is it safe to compare pointers of same type? -

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char** buffer{ /* buffer */ }; char* ptr1{buffer[0]}; char* ptr2{buffer[10]};  assert(ptr1 < ptr2);

if 2 pointers point different locations in same buffer, safe compare them?

i want know if range of pointers valid comparing: assert(rangebeginptr < rangeendptr).

you can compare pointers relational operators (<, >, <= , >=) provided both point element of same array, or 1 past array. else unspecified behaviour per c++11 5.9 relational operators. so, given:

char xyzzy[10]; char plugh[10];

all these specified function correctly:

assert(&(xyzzy[1]) < &(xyzzy[4])); assert(&(xyzzy[9]) < &(xyzzy[10])); // though [10] isn't there.

but these not:

assert(&(xyzzy[1]) < &(xyzzy[15])); assert(&(xyzzy[9]) < &(plugh[3]));

the type doesn't come except has same type if you're comparing 2 elements in same array. if have 2 char * variables, that's unspecified if point different arrays though have same type.


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