Concatenating strings in C, which method is more efficient?

Question

I came across these two methods to concatenate strings:

Common part:

char* first= \"First\";
char* second = \"Second\";
char* both = malloc(strlen(fi         


        

Answer 1

The difference is unlikely to matter:

• If your strings are small, the malloc will drown out the string concatenations.
• If your strings are large, the time spent copying the data will drown out the differences between strcat / sprintf.

As other posters have mentioned, this is a premature optimization. Concentrate on algorithm design, and only come back to this if profiling shows it to be a performance problem.

That said... I suspect method 1 will be faster. There is some---admittedly small---overhead to parse the sprintf format-string. And strcat is more likely "inline-able".