Shachar Shemesh wrote:
Benchmark will follow soon. In the mean time, think about the fact that, compared to linear copying of the strings in, these are the overheads (neglecting function call overhead, which is not neglectible but is fair):
n - number of strings in the final string
m(i) - length of string i (0<i<=n)
sm(i) - sigma of all lengths up to i (0<i<=n)
sm(n) - total length of all strings
with sprintf - parsing the format string*n+sm(n)
with strcpy+strcat - for each strcat we have to find the end of the string (sm(i-1)), and then write our own string (m(i)).
Shachar Shemesh wrote:
Was going to say earlier, but didn't get to it ... the reason is probably thatWhen I'm wrong, I'm wrong. sun@sun:~/sources/wine/test$ gcc -O0 strcpy.c -o way1 -DWAY1 sun@sun:~/sources/wine/test$ gcc -O0 strcpy.c -o way2 -DWAY2 sun@sun:~/sources/wine/test$ gcc -O0 strcpy.c -o way3 -DWAY3 sun@sun:~/sources/wine/test$ ./way1 Operation took 0 seconds 450763 usec sun@sun:~/sources/wine/test$ ./way2 Operation took 0 seconds 598408 usec sun@sun:~/sources/wine/test$ ./way3 Operation took 0 seconds 427037 usec
you were underestimating the time required to parse the format string,
which is probably greater than anything else. Everything else is simple
searching and copying whereas the parsing is probably at least a
quadratic-order function. Anyway you've now demonstrated that so
this isn't that relevant anymore...
David
