Compare memory pointers in Solidity

Question

Is there a way to compare pointers in Solidity?

I have two local variables:

uint256[] memory a = new uint256[](256);
uint256[] memory b = a;

If I try a == b I get this compiler error:

TypeError: Operator == not compatible with types uint256[] memory and uint256[] memory

Answer 1

One possible solution is to use the eq instruction in inline assembly:

uint256[] memory a = new uint256[](256);
uint256[] memory b = a;
bool aEqualsB;
assembly {
    aEqualsB := eq(a, b)
}
// aEqualsB now contains the value: true

b = new uint256[](256);
assembly {
    aEqualsB := eq(a, b)
}
// aEqualsB now contains the value: false