Does std::hash give same result for same input for different complied builds and different machines?


Does std::hash give same result for same input for different complied builds and different machines?



I have some random test parameters which I need to calculate a hash to detect if I ran with same parameters.
I might run the test using binary recompiled at different time or machine.
Also run on different machines?



Even so I want to detect whether the same parameters were used for the run.
Does std::hash give same result for same input for different complied builds and different machines?


std::hash



e.g.


std::hash<string>{}("TestcaseParamVal0.7Param0.4");



will this always be a unique number.





added example code
– Nelson Pinto
12 mins ago





@Oighea, not all questions need code, and this one in particular doesn't seem like it needs any to be clear and answerable.
– zneak
6 mins ago





Fact is, the original form is poorly formatted and paragraphed. That is why he got reminded.
– Oighea
1 min ago





1 Answer
1



No, std::hash does not guarantee that the result will be the same across computers, builds, or even executions of the same build on the same computer. Your only guarantee is that during one execution, objects that are equal have the same hash.


std::hash



If you need repeatability between executions and machines, you can't use std::hash and must roll out your own equivalent.


std::hash






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