cpp-utilities/tests/stringbuilder-bench.md

Simple/stupid benchmarking

Compares the string builder and numberToString() function as provided by c++utilities with std::stringstream (without reserving stringstream buffer).

The string builder is actually just a fancy syntax for std::string::reserve() making its use more convenient.

Compile and run

eg.

g++ -O3 stringbuilder-bench.cpp -o stringbuilder-bench-O3 -Wl,-rpath /lib/path -L /lib/path -lc++utilities
./stringbuilder-bench-O3

Results on my machine

Results with -03:

plus operator: 00:00:19
stringstream: 00:00:16
string builder: 00:00:05
diff (stringstream minus string builder): 00:00:11
factor (stringstream / string builder): 3.2

However, with -O0 4 times slower:

plus operator: 00:00:34
stringstream: 00:00:23
string builder: 00:01:02
diff (stringstream minus string builder): - 00:35:31
factor (stringstream / string builder): 0.370968

Still 2.42 times faster than stringstream with -O2:

plus operator: 00:00:21
stringstream: 00:00:17
string builder: 00:00:07
diff (stringstream minus string builder): 00:00:10
factor (stringstream / string builder): 2.42857

So this basic tests show that string builder is up to 3 times faster when using full optimization and still 2 times faster when using -O2 (default under Arch Linux). However, without optimization it way slower. Results with clang++ were similar.