浮点转字符串性能比较

1.浮点转字符串

使用 boost 1.56 里面的 karma 自带的测试用例，修改源码添加对 double conversion 的支持，同时输出结果为 markdown 表格。double conversion 优化级别O2，测试机为 CentOS 6.5 g++ 4.4.7。结果如下

 

[root@slave205 karma]# g++ double_performance.cpp /usr/local/lib/libdouble-conversion.a -lrt -O2
[root@slave205 karma]# for i in 123456789.0 5.0 0.123456 123456.7890123 0.0000123456 ; do echo ""; ./a.out $i ; done

method	time	result
sprintf	1.01284	123456789.000000
iostreams	1.11144	1.23457e+08
format	2.61989	123456789.000000
karma	0.534133	1.235e08
karma (string)	0.609746	1.235e08
karma (rule)	0.589086	1.235e08
karma (direct)	0.529474	1.235e08
double_conversion ToShortest	0.206492	123456789

method	time	result
sprintf	0.339345	5.000000
iostreams	0.58121	5
format	1.7414	5.000000
karma	0.229682	5.0
karma (string)	0.272013	5.0
karma (rule)	0.26701	5.0
karma (direct)	0.218975	5.0
double_conversion ToShortest	0.136092	5

method	time	result
sprintf	0.407084	0.123456
iostreams	0.692892	0.123456
format	2.07	0.123456
karma	0.208019	0.123
karma (string)	0.246272	0.123
karma (rule)	0.253367	0.123
karma (direct)	0.213895	0.123
double_conversion ToShortest	0.182453	0.123456

method	time	result
sprintf	1.00817	123456.789012
iostreams	1.04606	123457
format	2.67615	123456.789012
karma	0.528678	1.235e05
karma (string)	0.566756	1.235e05
karma (rule)	0.599371	1.235e05
karma (direct)	0.512787	1.235e05
double_conversion ToShortest	0.211471	123456.7890123

method	time	result
sprintf	0.456531	0.000012
iostreams	0.826126	1.23456e-05
format	2.06105	0.000012
karma	0.554503	1.235e-05
karma (string)	0.624482	1.235e-05
karma (rule)	0.593442	1.235e-05
karma (direct)	0.499671	1.235e-05
double_conversion ToShortest	0.219412	0.0000123456

注：CppFormat 的浮点转换为调用 sprintf 所以这里并没有测试它。

       迭代一百万次，时间单位秒

 

2.整数转字符串

可参考 http://zverovich.net/2013/09/07/integer-to-string-conversion-in-cplusplus.html