如何从php数组生成一个唯一的字符串

I need a unique string from an array so that I can tell when it changes without measuring the inputs of that array. I'm trying to work out if it is computationally efficient to calculate a value rather than add code to look out for changes in the array. The array itself can have a variety of values and for future proofing I don't want to try and measure whether new values have been added to the array, I'd much rather just create some string or hash that will change if the array itself changes.I need a unique string from an array so that I