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C++ UUID generator
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#ifndef UUID_H | |
#define UUID_H | |
#include <string> | |
#include <cstdlib> | |
//*Adapted from https://gist.github.com/ne-sachirou/882192 | |
//*std::rand() can be replaced with other algorithms as Xorshift for better perfomance | |
//*Random seed must be initialized by user | |
namespace MathUtils{ | |
const std::string CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; | |
std::string generateUUID(){ | |
std::string uuid = std::string(36,' '); | |
int rnd = 0; | |
int r = 0; | |
uuid[8] = '-'; | |
uuid[13] = '-'; | |
uuid[18] = '-'; | |
uuid[23] = '-'; | |
uuid[14] = '4'; | |
for(int i=0;i<36;i++){ | |
if (i != 8 && i != 13 && i != 18 && i != 14 && i != 23) { | |
if (rnd <= 0x02) { | |
rnd = 0x2000000 + (std::rand() * 0x1000000) | 0; | |
} | |
rnd >>= 4; | |
uuid[i] = CHARS[(i == 19) ? ((rnd & 0xf) & 0x3) | 0x8 : rnd & 0xf]; | |
} | |
} | |
return uuid; | |
} | |
#endif |
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I generated 1 lakh UUIds using this methodology. at 6k it lost its uniqueness and started producing duplicates