Add string_cast benchmark

[UdjinM6]

Benchmark various ways of dealing with int->string/string->int conversion.

Example output:

int_atoi,50331648,0.000000019404922,0.000000022758229,0.000000019926271,44,52,45
int_lexical_cast,11534336,0.000000086763293,0.000000091805305,0.000000088044255,199,211,202
strings_1_itostr,1966080,0.000000513366103,0.000000535408617,0.000000521111118,1182,1233,1200
strings_1_lexical_cast,4718592,0.000000208921847,0.000000232099410,0.000000228008503,481,534,525
strings_1_to_string,10485760,0.000000100358648,0.000000102645799,0.000000100982948,231,236,232
strings_2_multi_itostr,360448,0.000002753280569,0.000003013919923,0.000002918795376,6343,6943,6724
strings_2_multi_lexical_cast,786432,0.000001085310942,0.000001406770025,0.000001326184550,2500,3241,3055
strings_2_multi_to_string,1441792,0.000000722397090,0.000000758904207,0.000000734721074,1664,1748,1692
strings_2_strptintf,589824,0.000001733627869,0.000001917891495,0.000001835428621,3994,4418,4228

atoi and to_string (including concatenation of multiple items) seems to be the fastest option on my machine.

Somewhat complementary to #2072

[kxcd]

Hi @UdjinM6 , why not use the stringstream library for conversion from number to string? eg this function.

template <typename T>
string NumberToString(T Number){
	ostringstream oss;
	oss << Number;
	string s = oss.str();
	return s;
}

[UdjinM6]

Added suggested test. New results:

int_atoi,54525952,0.000000019187723,0.000000020333289,0.000000019527621,44,46,44
int_lexical_cast,11534336,0.000000087266926,0.000000093114977,0.000000088241057,201,214,203
strings_1_itostr,1966080,0.000000521271431,0.000000540641850,0.000000528914340,1200,1245,1218
strings_1_lexical_cast,4718592,0.000000200056093,0.000000250434823,0.000000233503720,460,576,537
strings_1_numberToString,2621440,0.000000394880772,0.000000445743353,0.000000415233990,909,1026,956
strings_1_to_string,10485760,0.000000099870704,0.000000117348691,0.000000104061701,230,270,239
strings_2_multi_itostr,360448,0.000002743763616,0.000002986227628,0.000002932206288,6321,6880,6755
strings_2_multi_lexical_cast,786432,0.000001107924618,0.000001390930265,0.000001324080282,2552,3204,3050
strings_2_multi_numberToString,458752,0.000002188346116,0.000002595712431,0.000002322154614,5041,5980,5350
strings_2_multi_to_string,1310720,0.000000747084414,0.000000861427907,0.000000764622564,1721,1984,1761
strings_2_strptintf,589824,0.000001804815838,0.000002314453013,0.000001858364461,4158,5332,4281

to_string is still the best one on my machine.

[gladcow]

ACK, my results (gcc 7.3.0, Ubuntu 18):

int_atoi,251658240,0.000000003801944,0.000000004374556,0.000000004149028,8,9,9
int_lexical_cast,37748736,0.000000026969417,0.000000033025231,0.000000029328191,59,72,64
strings_1_itostr,2097152,0.000000451080268,0.000000555111001,0.000000508656058,990,1218,1116
strings_1_lexical_cast,20971520,0.000000045198249,0.000000052876430,0.000000051077893,99,116,112
strings_1_numberToString,2359296,0.000000439768883,0.000000501906470,0.000000466112801,965,1101,1023
strings_1_to_string,9437184,0.000000103829279,0.000000119913238,0.000000108923486,227,263,239
strings_2_multi_itostr,360448,0.000002510467311,0.000003486631613,0.000002851645563,5510,7653,6259
strings_2_multi_lexical_cast,2097152,0.000000377578544,0.000000560081389,0.000000478372158,828,1229,1050
strings_2_multi_numberToString,327680,0.000002153799869,0.000003418790584,0.000003094021667,4727,7504,6791
strings_2_multi_to_string,1310720,0.000000636917321,0.000000819260094,0.000000769891994,1398,1798,1689
strings_2_strptintf,917504,0.000000909256414,0.000001291084118,0.000001130077830,1995,2833,2480

[nmarley]

ACK, results on my machine:

#Benchmark,count,min,max,average,min_cycles,max_cycles,average_cycles
int_atoi,402653184,0.000000002439265,0.000000002725031,0.000000002531824,7,8,7
int_lexical_cast,37748736,0.000000026514499,0.000000029156581,0.000000027592099,82,90,85
strings_1_itostr,3670016,0.000000260559318,0.000000292529876,0.000000283866614,806,905,878
strings_1_lexical_cast,23068672,0.000000042560714,0.000000046330911,0.000000045335861,131,143,140
strings_1_numberToString,4194304,0.000000240572263,0.000000267158612,0.000000253201733,744,827,783
strings_1_to_string,10485760,0.000000093335984,0.000000100010993,0.000000097110660,288,309,300
strings_2_multi_itostr,655360,0.000001461157808,0.000001609023457,0.000001529570000,4523,4981,4735
strings_2_multi_lexical_cast,3407872,0.000000305561116,0.000000327201633,0.000000317731694,946,1013,983
strings_2_multi_numberToString,786432,0.000001181877451,0.000001402939233,0.000001303474467,3659,4343,4035
strings_2_multi_to_string,1835008,0.000000559066393,0.000000612424628,0.000000576249736,1730,1896,1784
strings_2_strptintf,851968,0.000001143522240,0.000001270400389,0.000001198567099,3540,3933,3710