A howl on the wind…

A performance benchmark of which include guard method is faster. Test times the compilation of a main.cpp that includes 10000 files 3 times each.

The tested methods are:

• #pragma once followed by #ifndef
• #ifndef followed by #pragma once
• Only #pragma once
• Only #ifndef
• External #ifndef

Sources for the test is at inc.tar.gz, but it’s just 5×10000 files.

The compilers are Microsoft Visual C++ 2010, GNU g++ 4.6.1, and LLVM clang++ 2.9.

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(There is also a string-to-int performance test.)

A performance benchmark of which method is faster of converting an std::string to a double. The goal is ending up with a double of the value represented in an std::string.

The tested methods are:

• a hand-written naive loop
• atof()
• strtod()
• sscanf()
• boost::lexical_cast<double>()
• boost::spirit::qi::parse()
• std::stringstream
• std::stringstream, reusing the object

Source for the test is at speed-string-to-double.cpp with cycle.h.

The compilers are Microsoft Visual C++ 2010 with _SECURE_SCL disabled, GNU g++ 4.6.0, and LLVM clang++ from Arch.

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Your BrainHex Class is Mastermind.

Your BrainHex Sub-Class is Mastermind-Seeker.

You like solving puzzles and devising strategies as well as finding strange and wonderful things or finding familiar things.

Each BrainHex Class also has an Exception, which describes what you dislike about playing games. Your Exceptions are:

» No Fear: You do not enjoy feeling afraid, preferring to feel safe or in control.

Your scores for each of the classes in this test were as follows:

Mastermind: 20
Seeker: 17
Achiever: 13
Socialiser: 7
Daredevil: 4
Conqueror: 2
Survivor: -2

A performance comparison of the speed of various ways to compare strings in C++. In this test, all comparisons are of not-equal strings.

Idea from #C++ on QuakeNet, where we always advocate using std::string over various char* functions. I wondered what, if any, the penalty for doing so was.

Sources

• Ticks counted via cycle.h (local mirror)
• Source: speed-string-compare.cpp

Things Tested

• a hand-written naive comparator loop; used as baseline
• string == string
• string == const char*
• strcmp(const char*, const char*) == 0
• strcmp(const char*, string.c_str()) == 0
• strcmp(string.c_str(), string.c_str()) == 0
• string.compare(string)
• string.compare(const char*)
• …and then the whole thing with different offsets.

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A performance comparison of the speed of various ways to read an entire file into an std::string in C++.

Idea from BD-Calvin in #C++ on QuakeNet.

Sources

• Ticks counted via cycle.h (local mirror)
• Source: speed-read-whole-file.cpp
• File used was generated with dd if=/dev/urandom of=random100 bs=1M count=100

Things Tested

• writing to a stringstream, then pulling data out as string
• constructing a string via streambuf_iterator
• getting file size via seeking, then preallocating a string to read into
• getting file size via stat(), then ditto…

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