strcpy, lstrcpy 相关API实现字符串COPY, 性能之比较

最新推荐文章于 2022-03-14 00:07:18 发布

davemin

最新推荐文章于 2022-03-14 00:07:18 发布

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分类专栏： System 文章标签： api 测试优化

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本文对比了VC6和VS2008环境下，strcpy、lstrcpy、lstrcpyn、strncpy、memcpy以及自定义my_memcpy和StrNCpy在不同循环次数下的性能表现。测试结果显示，memcpy在某些情况下性能为0，lstrcpy在不依赖runtime lib的情况下表现出良好的性能，建议更多使用。

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n长度: 25, 字符串总长度: 56
字符串总长度: 57的测试也作了, 与此结果差不多.
时间单位:tick

测试结果如下:

编绎器: VC6

RELEASE
1亿次循环测试结果:
lstrcpy=7437
strcpy = 13047
lstrcpyn = 6797
strncpy = 1672
memcpy = 0
my_memcpy = 1313
StrNCpy = 6812

1KW次循环测试结果:
lstrcpy=734
strcpy = 1313
lstrcpyn = 672
strncpy = 156
memcpy = 0
my_memcpy = 125
StrNCpy = 688

100W次循环测试结果:
lstrcpy=78
strcpy = 125
lstrcpyn = 78
strncpy = 16
memcpy = 0
my_memcpy = 15
StrNCpy = 63

DEBUG:
1亿次循环测试结果:
lstrcpy=7734
strcpy = 2172
lstrcpyn = 7469
strncpy = 1922
memcpy = 1031
my_memcpy = 5437
StrNCpy = 7453

1KW次循环测试结果:
lstrcpy=765
strcpy = 219
lstrcpyn = 734
strncpy = 204
memcpy = 93
my_memcpy = 547
StrNCpy = 750

100W次循环测试结果:
lstrcpy=78
strcpy = 31
lstrcpyn = 63
strncpy = 31
memcpy = 0
my_memcpy = 63
StrNCpy = 78

VS2008 VC 测试:

RELEASE
1亿次循环测试结果:
lstrcpy=7391
strcpy = 4500
lstrcpyn = 6093
strncpy = 1735
memcpy = 0
my_memcpy = 1140
StrNCpy = 6094

1KW次循环测试结果:
lstrcpy=734
strcpy = 454
lstrcpyn = 609
strncpy = 172
memcpy = 0
my_memcpy = 109
StrNCpy = 610

100W次循环测试结果:
lstrcpy=78
strcpy = 47
lstrcpyn = 47
strncpy = 31
memcpy = 0
my_memcpy = 0
StrNCpy = 63

DEBUG:
1亿次循环测试结果:
lstrcpy=7734
strcpy = 2797
lstrcpyn = 6797
strncpy = 2094
memcpy = 1094
my_memcpy = 7593
StrNCpy = 6860

1KW次循环测试结果:
lstrcpy=781
strcpy = 282
lstrcpyn = 687
strncpy = 203
memcpy = 110
my_memcpy = 765
StrNCpy = 688

100W次循环测试结果:
lstrcpy=78
strcpy = 32
lstrcpyn = 62
strncpy = 31
memcpy = 0
my_memcpy = 78
StrNCpy = 79

memcpy 为什么总为:0 ?
关memcpy 性能参考: VC 对 memcpy 的优化:http://blog.codingnow.com/2005/10/vc_memcpy.html

结果:
1. CPU只用一个核
2. VS2008 作了相关优化, 在strcpy上与vc6 有很大不同.
3. lstrcpy 性能过的去, 并且不依赖runtime lib, 应该更多使用.