代码功能&＃xff1a;循环拼接字符串&＃xff0c;并替换子字符串
硬件环境&＃xff1a;Intel Core2 Duo T7500&＃64;2.20Ghz CPU; 2 GB RAM; OS Debian GNU/Linux 2.6.32 i686
代码执行时长
代码性能对比图
最慢: Java gcj (native executable)
较慢: Java (openJDK); Java (Sun); Lua
稍慢: tcl; Javascript (spidermonkey)
较快: Python; Ruby; PHP; C&＃43;&＃43;; Javascript V8; C; Perl5
最快的是Perl&＃xff0c;最慢的gcj&＃xff0c;你能接受吗&＃xff1f;
内存使用情况
内存对比图&＃xff1a;
测试源码&＃xff1a;
C (source); Result: C gcc (Debian 4.4.4-1) 4.4.4
#include
#include
#include
#include
int main(){
setbuf(stdout,NULL); //disable output buffering
char *str&＃61;malloc(8);
strcpy(str,"abcdefgh");
str&＃61;realloc(str,strlen(str)&＃43;8);
strcat(str,"efghefgh"); //sprintf(str,"%s%s",str,"efghefgh");
int imax&＃61;1024/strlen(str)*1024*4;
printf("%s","exec.tm.sec\tstr.length\n"); //fflush(stdout);
time_t starttime&＃61;time(NULL);
char *gstr&＃61;malloc(0);
int i&＃61;0;
char *pos;
int lngth;
char *pos_c&＃61;gstr;
int str_len&＃61;strlen(str);
while(i&＃43;&＃43; lngth&＃61;strlen(str)*i;
gstr&＃61;realloc(gstr,lngth&＃43;str_len);
strcat(gstr,str); //sprintf(gstr,"%s%s",gstr,str);
pos_c&＃43;&＃61;str_len;
pos&＃61;gstr;
while(pos&＃61;strstr(pos,"efgh")){
memcpy(pos,"____",4);
}
if(lngth % (1024*256)&＃61;&＃61;0){
printf("%dsec\t\t%dkb\n",time(NULL)-starttime,lngth/1024); //fflush(stdout);
}
}
//printf("%s\n",gstr);
}
C&＃43;&＃43; (source) Result: C&＃43;&＃43; g&＃43;&＃43; (Debian 4.4.3-7) 4.4.3
#include
#include
#include
using namespace std;
main ()
{
string str &＃61; "abcdefgh";
str &＃43;&＃61; "efghefgh";
int imax &＃61; 1024 /str.length() * 1024 *4;
time_t currentTime &＃61; time(NULL);
cout <<"exec.tm.sec\tstr.length" <string find&＃61; "efgh";
string replace &＃61;"____";
string gstr;
int i&＃61;0;
int length;
// int end&＃61;0; // size_t end&＃61;0;
while(i&＃43;&＃43; gstr &＃43;&＃61; str;
gstr &＃61; gstr;
size_t start, sizeSearch&＃61;find.size(), end&＃61;0;
while((start&＃61;gstr.find(find,end))!&＃61;string::npos){
end&＃61;start&＃43;sizeSearch;
gstr.replace(start,sizeSearch,replace);
}
length &＃61; str.length()*i;
if((length%(1024 * 256))&＃61;&＃61;0){
cout <}
}
// cout <return 0;
}
Javascript (source); Results: Javascript (Spidermonkey - Mozilla) 1.8.0 pre-release 1 2007-10-03,
Javascript (V8 - Chrome)
#!/usr/local/bin/js
var str &＃61; "abcdefgh"&＃43;"efghefgh";
var imax &＃61; 1024 / str.length * 1024 * 4;
var time &＃61; new Date();
print("exec.tm.sec\tstr.length");
var gstr &＃61; "";
var i&＃61;0;
var lngth;
while (i&＃43;&＃43; gstr &＃43;&＃61; str;
gstr &＃61; gstr.replace(/efgh/g, "____");
lngth&＃61;str.length*i;
if ((lngth % (1024*256)) &＃61;&＃61; 0) {
var curdate&＃61;new Date();
print(parseInt(((curdate.getTime()-time.getTime())/1000))&＃43;"sec\t\t"&＃43;lngth/1024&＃43;"kb");
}
}
Java (source) Results: Java (OpenJDK) "1.6.0 18",
Java (Sun) "1.6.0 16",
Java (gcj) (Debian 4.4.3-1) 4.4.3
public class java_test {
public static final void main(String[] args) throws Exception {
String str &＃61; "abcdefgh"&＃43;"efghefgh";
int imax &＃61; 1024 / str.length() * 1024 * 4;
long time &＃61; System.currentTimeMillis();
System.out.println("exec.tm.sec\tstr.length\tallocated memory:free memory:memory used");
Runtime runtime &＃61; Runtime.getRuntime();
System.out.println("0\t\t0\t\t"&＃43;runtime.totalMemory()/1024 &＃43;":"&＃43; runtime.freeMemory()/1024&＃43;":"&＃43;(runtime.totalMemory()-runtime.freeMemory())/1024);
String gstr &＃61; "";
int i&＃61;0;
int lngth;
while (i&＃43;&＃43; gstr &＃43;&＃61; str;
gstr &＃61; gstr.replaceAll("efgh", "____");
lngth&＃61;str.length()*i;
if ((lngth % (1024*256)) &＃61;&＃61; 0) {
System.out.println(((System.currentTimeMillis()-time)/1000)&＃43;"sec\t\t"&＃43;lngth/1024&＃43;"kb\t\t"&＃43;runtime.totalMemory()/1024&＃43;":"&＃43;runtime.freeMemory()/1024&＃43;":"&＃43;(runtime.totalMemory()-runtime.freeMemory())/1024);
}
}
}
}
Perl5 (source); Result: This is perl, v5.10.1
#!/usr/bin/perl
$|&＃61;1; #disable output buffering, this is necessary for proper output through pipe
my $str&＃61;&＃39;abcdefgh&＃39;.&＃39;efghefgh&＃39;;
my $imax&＃61;1024/length($str)*1024*4; # 4mb
my $starttime&＃61;time();
print "exec.tm.sec\tstr.length\n";
my $gstr&＃61;&＃39;&＃39;;
my $i&＃61;0;
while($i&＃43;&＃43; <$imax&＃43;1000){ #adding 1000 iterations to delay exit. This will allow to capture memory usage on last step
$gstr.&＃61;$str;
$gstr&＃61;~s/efgh/____/g;
my $lngth&＃61;length($str)*$i; ## my $lngth&＃61;length($gstr); # Perhaps that would be a slower way
print time()-$starttime,"sec\t\t",$lngth/1024,"kb\n" unless $lngth % (1024*256); #print out every 256kb
}
PHP (source); Result: PHP 5.3.1-5 with Suhosin-Patch (cgi-fcgi)
$str&＃61;"abcdefgh"."efghefgh";
$imax&＃61;1024/strlen($str)*1024*4; # 4mb
$starttime&＃61;time();
print("exec.tm.sec\tstr.length\n");
$gstr&＃61;&＃39;&＃39;;
$i&＃61;0;
while($i&＃43;&＃43; <$imax&＃43;1000){
$gstr.&＃61;$str;
$gstr&＃61;preg_replace(&＃39;/efgh/&＃39;,&＃39;____&＃39;,$gstr);
$lngth&＃61;strlen($str)*$i;
if($lngth % (1024*256)&＃61;&＃61;0){
print (time()-$starttime."sec\t\t".($lngth/1024)."kb\n");
}
}
?>
Python3 (source); Result: Python 3.1.3
#!/usr/bin/python3 -u
import re
import time
import sys
str&＃61;&＃39;abcdefgh&＃39;&＃43;&＃39;efghefgh&＃39;
imax&＃61;1024/len(str)*1024*4 # 4mb
starttime&＃61;time.time();
print "exec.tm.sec\tstr.length"
sys.stdout.flush()
gstr&＃61;&＃39;&＃39;
i&＃61;0
while (i i&＃61;i&＃43;1
gstr&＃43;&＃61;str
gstr&＃61;re.sub(&＃39;efgh&＃39;,&＃39;____&＃39;,gstr)
lngth&＃61;len(str)*i
if(lngth % (1024*256) &＃61;&＃61; 0):
print int(time.time()-starttime),"sec\t\t",(lngth/1024),"kb"
sys.stdout.flush()
Ruby (source); Result: ruby 1.8.7
#!/usr/bin/ruby
$stdout.sync&＃61;true;
str&＃61;&＃39;abcdefgh&＃39;&＃43;&＃39;efghefgh&＃39;;
imax&＃61;1024/str.length*1024*4; # 4mb
starttime&＃61;Time.new;
print("exec.tm.sec\tstr.length\n");
gstr&＃61;&＃39;&＃39;;
i&＃61;0;
while i i&＃61;i&＃43;1;
gstr&＃43;&＃61;str;
gstr&＃61;gstr.gsub(/efgh/, "____")
lngth&＃61;str.length*i;
if(lngth % (1024*256)&＃61;&＃61;0)
print(((Time.new-starttime).ceil).to_s&＃43;"sec\t\t",(lngth/1024).to_s,"kb\n");
end
end
#puts gstr;
Lua (source); Result: Lua 5.1.4
#!/usr/bin/lua
io.stdout:setvbuf "no"; -- io.flush();
str&＃61;&＃39;abcdefgh&＃39;..&＃39;efghefgh&＃39;;
imax&＃61;1024/string.len(str)*1024*4; -- 4mb
starttime&＃61;os.time();
print "exec.tm.sec\tstr.length";
gstr&＃61;&＃39;&＃39;;
i&＃61;0;
while i i&＃61;i&＃43;1;
gstr&＃61;gstr..str;
gstr&＃61;string.gsub(gstr,"efgh","____");
lngth&＃61;string.len(str)*i;
if(math.mod(lngth,1024*256)&＃61;&＃61;0) then
print(os.time()-starttime.."sec\t\t"..(lngth/1024).."kb");
end
end
tcl (source); Result: tcl 8.4.19
#!/usr/bin/tclsh
set str "abcdefgh"
append str "efghefgh"
set imax [expr {1024/[string length $str]*1024*4}]
set starttime [clock clicks -milliseconds]
puts "exec.tm.sec\tstr.length";
set gstr ""
set i 0
while {$i<[expr {$imax&＃43;1000}]} {
incr i
append gstr $str;
regsub -all {efgh} $gstr ____ gstr
set lngth [expr {[string length $str]*$i}]
if {[expr {$lngth % (1024*256)}] &＃61;&＃61; 0} {
puts "[expr int([expr [clock clicks -milliseconds] - $starttime] / 1000)]sec\t\t[expr {$lngth/1024}]kb"
}
}
exit
结论
各语言随着版本升级&＃xff0c;也在不断优化&＃xff0c;想要用好每个语言的特性&＃xff0c;需要摸透她的脾气&＃xff0c;这个需要不断的加深了解。
选语言就像选恋人&＃xff0c;情人眼里出西施&＃xff0c;你中意的&＃xff0c;就是最好的&＃xff0c;所以对以上结果别太较真。
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