c# - Converting a hex string to its BigInteger equivalent negates the value -

i have string represents large hexadecimal number want convert integer. when try convert though, answer integer equivalent negative. here's code:

string hex = "9782e78f1636";  biginteger b1 = biginteger.parse(hex, numberstyles.allowhexspecifier); 

how can correct result?

you need prepend 0 string. while number works long.parse, bigint negative number if first digit between 8-f

string hex = "09782e78f1636";       biginteger b1 = biginteger.parse(hex,numberstyles.allowhexspecifier);     console.writeline(b1); 

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it's been long time, feel should have explained why:

signed integers use significant bit (msb) indicates whether value positive or negative. although there's more msb.

both biginteger , long signed integers: if significant number in hex string between 0 (0000) , 7 (0111), msb 0 , number positive. if it's 8 (1000) or above, msb 1 , number negative.

long.parse knows size of type you're parsing, ie it's hex representation 00009782e78f1636. msb 0 it's clealy positive.

bigint isn't of fixed size long. if give 9782e78f1636 it doesn't know mean same 00001782e78f1636. thinks type shorter. it's expecting signed value , it thinks mean first bit of 9 (1001) sign. adding 0 front 09782e78f1636 makes clear msl bit 0 , 1001 part of actual value.