How to get hash value of an object?

panmengh via Digitalmars-d-learn Sat, 26 Nov 2016 23:15:57 -0800

How to get hash value of an object?

Use hashOf? or typeid(T).getHash(&o)?


I test with the following code:

System:
windows 10

dmd --version
DMD32 D Compiler v2.072.0 (official download version)

ldc2 --version

LDC - the LLVM D compiler (1.1.0git-62a2252) (the latest gitmaster version)

  based on DMD v2.071.2 and LLVM 3.9.1git

import std.stdio;

void main()
{
    string[string] a;
    string[string] b0;

writeln(a.hashOf(), "\t\t",typeid(typeof(a)).getHash(&a),"\t\t\t",b0.hashOf(), "\t\t",typeid(typeof(b0)).getHash(&b0), "", a,);


    a["1"] = "1";
    string[string] b1 = ["1":"1"];

writeln(a.hashOf(), "\t\t",typeid(typeof(a)).getHash(&a),"\t\t",b1.hashOf(), "\t\t",typeid(typeof(b1)).getHash(&b1), "", a,);


    a["9"] = "9";
    string[string] b2 = ["1":"1", "9":"9"];

writeln(a.hashOf(), "\t\t",typeid(typeof(a)).getHash(&a),"\t\t\t",b2.hashOf(), "\t\t",typeid(typeof(b2)).getHash(&b2), "", a,);


    a["3"] = "3";
    string[string] b3 = ["1":"1", "9":"9", "3":"3"];

writeln(a.hashOf(), "\t\t",typeid(typeof(a)).getHash(&a),"\t\t",b3.hashOf(), "\t\t",typeid(typeof(b3)).getHash(&b3), "", a,);


    a.remove("1");
    a["1"] = "1";
    string[string] b4 = ["1":"1", "9":"9", "3":"3"];

writeln(a.hashOf(), "\t\t",typeid(typeof(a)).getHash(&a),"\t\t",b3.hashOf(), "\t\t",typeid(typeof(b4)).getHash(&b4), "", a,);

}

Output:
dub --compiler=dmd -a=x86_64
Running .\test2.exe
1669671676      0           1669671676  0           []
732702303       2197205690  683765274   3388425732  ["1":"1"]

732702303 0 912895782 0 ["1":"1","9":"9"]732702303 2197205690 4139255736 3388425732 ["3":"3","1":"1", "9":"9"]732702303 2197205690 4139255736 3388425732 ["3":"3","1":"1", "9":"9"]


test2.exe (second run)
1669671676      0           1669671676  0           []
1608602074      122060002   2487796584  31054674    ["1":"1"]

1608602074 0 3256818953 0 ["1":"1","9":"9"]1608602074 122060002 667025292 31054674 ["3":"3","1":"1", "9":"9"]1608602074 122060002 667025292 31054674 ["3":"3","1":"1", "9":"9"]


dub --compiler=ldc2 -a=x86_64
Running .\test2.exe
593689054       0           593689054   0           []
1747365348      1899073920  1747365348  1899073920  ["1":"1"]

3252326176 0 3252326176 0 ["1":"1","9":"9"]492636279 1899073920 492636279 1899073920 ["3":"3","1":"1", "9":"9"]492636279 1899073920 492636279 1899073920 ["3":"3","1":"1", "9":"9"]


test2.exe (second run)
593689054       0           593689054   0           []
1747365348      2353409518  1747365348  2353409518  ["1":"1"]

3252326176 0 3252326176 0 ["1":"1","9":"9"]492636279 2353409518 492636279 2353409518 ["3":"3","1":"1", "9":"9"]492636279 2353409518 492636279 2353409518 ["3":"3","1":"1", "9":"9"]


Does only hashOf with ldc2 return the right value?

How to get hash value of an object?

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