C/C++&Java 字符串拼接效率对比（下部）[内容超过长度被截断完成可以下载文档和源码]

C/C++字符串拼接测试运行结果：

 

Release version.

TEST_TIME: 90000

C language memcpy append Used: 0 ms.

string length: 630000

std::string += operator Used: 15 ms.

string length: 630000

std::string append Used: 16 ms.

string length: 630000

std::ostringstream << Used: 16 ms.

string length: 630000

capacity: 630015

size: 0

hava resize(PREALLOCATE_SIZE) std::string += operator Used: 0 ms.

string length: 630000

MFC CString append Used: 63 ms.

string length: 630000

MFC CString operator append Used: 62 ms.

string length: 630000

c string function strcat: Used: 32203 ms.

string length: 630000

---------Statistics informations(sorting ascendent)-------

 

sort order: 1

item: C language memcpy append

used: 0 ms.

 

sort order: 2

item: hava resize(PREALLOCATE_SIZE) std::string += operator

used: 0 ms.

 

sort order: 3

item: std::string += operator

used: 15 ms.

 

sort order: 4

item: std::string append

used: 16 ms.

 

sort order: 5

item: std::ostringstream <<

used: 16 ms.

 

sort order: 6

item: MFC CString operator append

used: 62 ms.

 

sort order: 7

item: MFC CString append

used: 63 ms.

 

sort order: 8

item: c string function strcat:

used: 32203 ms.

 

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Press any key to continue . . .

Java的测试代码段:

void testJavaStringPerformance() {

final int TEST_TIMES = 90000;

       //String

       String str = new String();

 

       System.out.println("The testing is running, please wait...");

       long start = System.currentTimeMillis();       

       for (int i=0; i<TEST_TIMES; i++) {

              str += "cppmule";

       }

       long strUsed = System.currentTimeMillis() - start;

       System.out.println("strUsed: " + strUsed + " ms.");

      

//StringBuffer

       start = 0;

       StringBuffer strBuffer = new StringBuffer();

       start = System.currentTimeMillis();

       for (int i=0; i<TEST_TIMES; i++) {

              strBuffer.append("cppmule");

       }

       long strBufferUsed = System.currentTimeMillis() - start;

       System.out.println("StringBuffer append: " + strBufferUsed + " ms.");

      

       //StringBuilder

       start = 0;

       StringBuilder strBuilder = new StringBuilder();

       start = System.currentTimeMillis();

       for (int i=0; i<TEST_TIMES; i++) {

              strBuilder.append("cppmule");

       }

       long strBuilderUsed = System.currentTimeMillis() - start;

       System.out.println("StringBuilder append: " + strBuilderUsed + " ms.");

       System.out.println("Times: " + TEST_TIMES);

}

Java字符串拼接运行结果:

 

The testing is running, please wait...

strUsed: 443141 ms.

StringBuffer append: 15 ms.

StringBuilder append: 31 ms.

Times: 90000

 

Author:

By: cppmule

Email: [e-mail]

 

 

 

 

评论

16 楼 xjlfu 2011-02-01  

看过StringBuilder的代码就知道，StringBuilder就是apache的FastStringBuffer

15 楼 sam0411 2011-01-30  

StringBuffer and StringBuilder 的测试结果真是严重颠覆我的认知了,等我运行一下的。

14 楼 feiyan35488 2011-01-26  

willpower88 写道

willpower88 写道

jdk5.0后的版本会把new StringBuffer("afdsd").append("def");转为 "afdsd" + "def"的

不过可能和 我的反编译软件有关，我用的是cavaj

java 字符串拼接中
+ 号最慢，当数据量到 W级别时，时间是 +s
buffer  其次 ----------------        +10ms
builder 最快了 这是进程安全的。      +ms

对lz 的例子 保持强烈的怀疑。

to ls: 反编译是不精确的，建议看源代码

13 楼 willpower88 2011-01-26  

willpower88 写道

jdk5.0后的版本会把new StringBuffer("afdsd").append("def");转为 "afdsd" + "def"的

不过可能和 我的反编译软件有关，我用的是cavaj

12 楼 willpower88 2011-01-26  

jdk5.0后的版本会把new StringBuffer("afdsd").append("def");转为 "afdsd" + "def"的

11 楼 czwlucky 2011-01-25  

F:\Java2>java -version
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode, sharing)

F:\Java2>java TestString
The testing is running, please wait...
strUsed: 383672 ms.
StringBuffer append: 15 ms.
StringBuilder append: 0 ms.
Times: 90000

F:\Java2>java -server TestString
The testing is running, please wait...
strUsed: 290110 ms.
StringBuffer append: 15 ms.
StringBuilder append: 0 ms.
Times: 90000

10 楼 lxs647 2011-01-24  

build and buffer

的结果很怀疑、、、

9 楼 aninfeel 2011-01-21  

偶测过，stringbuffer不可能有stringbuilder快的，在7次拼装一下+都比stringbuffer快。

8 楼 skzr.org 2011-01-21  

ansjsun 写道

我记得+也挺快的么..估计写道for循环里..jdk不做优化了..

“记得”就是感觉吧

打开class文件看看+的实现就知道他们之间的区别了！

区别：1 对象创建个数 2 线程安全

7 楼 ansjsun 2011-01-21  

我记得+也挺快的么..估计写道for循环里..jdk不做优化了..

6 楼 ansjsun 2011-01-21  

我对你测试结果标识怀疑.你等等 啊

5 楼 ansjsun 2011-01-21  

你直接用加号 +++++ 都比StringBuffer 快 stringbuffer是线程安全的吧

4 楼 wesker0918 2011-01-20  

The testing is running, please wait...
strUsed: 57125 ms.
StringBuffer append: 16 ms.
StringBuilder append: 0 ms.
Times: 90000

3 楼 skzr.org 2011-01-11  

StringBuffer append: 48 ms.
StringBuilder append: 14 ms.
Times: 90000

2 楼 mercyblitz 2011-01-11  

这个好像没有什么可比性。除掉调式信息+server模式再试下！

1 楼 苍山洱海 2011-01-10  

StringBuffer  竟然比 StringBuilder快一倍。这是怎么个情况？

StringBuffer可是线程安全的，虽然程序没用到多线程，但怎么也比StringBuilder要多耗一点时间吧。。