为什么错误是表达式不是可修改的左值

Question

Answer 1

因为b的类型是int(*)[2]，b[i]的类型是int [2]，是一个数组类型，C/C++不允许对一个数组类型直接赋值。
把b[i] = a[i]改为b=a，这里是指针赋值

FROM https://en.cppreference.com/w/cpp/language/array#Assignment

Objects of array type cannot be modified as a whole: even though they are lvalues (e.g. an address of array can be taken), they cannot appear on the left hand side of an assignment operator: