Question

I bind a UUID value from a SQL SERVER colomn (via Qt Sql module) into a QUuid object.
After that I have to assign it into a in-house uuid object by using a assign function which take a char* as parameter.

QUuid expose several char* as public members, so I have to built a char * of 16 bytes with the several char * QUuid’s members.

namely, copy :

char buff0;
char buff1;
char buff2[2];
char buff3[4];
char buff4[8];

inside

char final[16];

I have used memcpy to do this task like that :

int accu = 0;    
memcpy(final, &buff0, sizeof(buff0)); 
accu += sizeof(buff1);
memcpy(final+accu, &buff1, sizeof(buff1));
accu += sizeof(buff2);
memcpy(final+accu, buff2, sizeof(buff2));
accu += sizeof(buff3);
memcpy(final+accu, buff3, sizeof(buff3));
accu += sizeof(buff4);
memcpy(final+accu, buff4, sizeof(buff4));

but I find this manner of doing not really readable and maintanable.
I’m looking for a more elegant manner to do this task. By elegant I mean with less line of codes and/or less arithmetics.

Answer 1

Here’s a C++11 STL version.

char* out = final;
out = std::copy_n(&buff0, 1, out);
out = std::copy_n(&buff1, 1, out);
out = std::copy_n(buff2, 2, out);
out = std::copy_n(buff3, 4, out);
out = std::copy_n(buff4, 8, out);