【LoadRunner技术讲座8】LoadRunner函数中的几个陷阱

柔光的暖阳◎ 2022-04-08 14:57 250阅读 0赞

无意中看到此文，写的不错，分享，原文如下：

1、atof

在**LoadRunner**中如果直接用：

输出的结果会是1244128.00，根本不是我们想要的。

因为float，double型在不同的平台下长度不一样，所以在loadrunner中调用atof需要显式的声明这个**函数**。

如下：

<table style="margin-left:0px;line-height:normal;border-right-color:rgb(153,153,153);border-right-width:1px;border-right-style:solid;border-top-color:rgb(153,153,153);border-top-width:1px;border-top-style:solid;font-size:12px;border-left-color:rgb(153,153,153);border-left-width:1px;border-left-style:solid;width:674px;border-bottom-color:rgb(153,153,153);border-bottom-width:1px;border-bottom-style:solid;font-family:'Courier new';background-color:rgb(221,221,221);"> 
 <tbody> 
  <tr> 
   <td style="margin-left:0px;font-size:12px;font-family:Verdana, '宋体', sans-serif;line-height:18px;"> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　doubleatof (const char *string);</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　float f;</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　f=atof("123.00");</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　lr_output_message("%.2f",f);</p> </td> 
  </tr> 
 </tbody> 
</table>

这样就能输出结果：123.00。

其实，在LR关于atof的帮助文档描述中有提到这点，要求使用这个函数前“must be explicitly declared in Vugen scripts. ”，同样的要求也出现在atol函数的描述中。

**2、lr.save\_string**

在LoadRunner中，使用.NET VUser时可以使用lr.save\_string来存入一个变量，但是其使用方法却与通常使用的lr\_save\_string有区别，不小心的话容易“中招”。

C语言的lr\_save\_string的定义如下：

注意：参数值在前面，参数名在后面。

而.NET VUser的lr.save\_string的参数使用恰好相反，参数名在前面，参数值应该放到后面。

但是LR的帮助文档并没有关于lr.save\_string的定义，如果在脚本中选中“lr.save\_string”，然后按F1，则直接蹦到lr\_save\_string的定义描述中，极容易误导人！

**3、ftp\_put**

ftp\_put 是LoadRunner中的FTP函数，用于上传文件到FTP服务器。定义如下：

查看LR的帮助文档可获得如下例子：

<table style="margin-left:0px;line-height:normal;border-right-color:rgb(153,153,153);border-right-width:1px;border-right-style:solid;border-top-color:rgb(153,153,153);border-top-width:1px;border-top-style:solid;font-size:12px;border-left-color:rgb(153,153,153);border-left-width:1px;border-left-style:solid;width:674px;border-bottom-color:rgb(153,153,153);border-bottom-width:1px;border-bottom-style:solid;font-family:'Courier new';background-color:rgb(221,221,221);"> 
 <tbody> 
  <tr> 
   <td style="margin-left:0px;font-size:12px;font-family:Verdana, '宋体', sans-serif;line-height:18px;"> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　// Send the file "ftp_file.txt" to the for_jon directory.</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ftp_put("Ftp_Put",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　"PATH=f:/ftp_file.txt", "TARGET_PATH=/pub/for_jon", "MODE=ASCII",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ENDITEM ,</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　LAST);</p> </td> 
  </tr> 
 </tbody> 
</table>

当你兴匆匆地以为拿过来修改一下就可以用了的时候，LR却提示如下错误:

Starting action Action.

globals.h(101): Warning message:PATH=D:/ftp.txt is not ftp\_put valid option

globals.h(101): Debug message:Putting file test.txt in /Qdownload/test.txt, passive mode set to 0

globals.h(101): Error -86026:Failed to open D:\\LoadRunner\\LRProject\\lr\_FTP1\\test.txt for reading.

globals.h(101): Error -86027:Failed to put data: 226 Transfer complete

Abort was called from an action.

提示错误是文件不能读，但是文件明明就不在错误所提示的D:\\LoadRunner\\LRProject\\lr\_FTP1\\test.txt 中，而是在D:/ftp.txt。

后来看到错误提示之前的一个Warning写道PATH=D:/ftp.txt is not ftp\_put valid option，难道错误是这里引起的？查看帮助文档关于item\_list的描述可知：

item\_list

A list of all the items for this function. Enclose all entries with quotes.

SOURCE\_PATH: The file to upload to the FTP server.

MSOURCE\_PATH - Like SOURCE\_PATH, but using wildcards to specify multiple files. If wildcards are not specified, all the files in the MSOURCE\_PATH are uploaded.

TARGET\_PATH (optional) - the path and filename in which to place the file.

if (M)SOURCE\_PATH is specified, but TARGET\_PATH is not specified, the file is stored in the root directory of the FTP server, with the original file name.

MODE (optional) - Retrieval mode ASCII or BINARY (default).

PASSIVE (optional) - Sets the communication protocol to Passive Mode FTP. To enable, pass "PASSIVE=TRUE".

ENDITEM - Marks the end of the list. (no quotes)

原来是SOURCE\_PATH而不是例子所说的PATH，好吧，等你改成SOURCE\_PATH后，如下所示：

<table style="margin-left:0px;line-height:normal;border-right-color:rgb(153,153,153);border-right-width:1px;border-right-style:solid;border-top-color:rgb(153,153,153);border-top-width:1px;border-top-style:solid;font-size:12px;border-left-color:rgb(153,153,153);border-left-width:1px;border-left-style:solid;width:674px;border-bottom-color:rgb(153,153,153);border-bottom-width:1px;border-bottom-style:solid;font-family:'Courier new';background-color:rgb(221,221,221);"> 
 <tbody> 
  <tr> 
   <td style="margin-left:0px;font-size:12px;font-family:Verdana, '宋体', sans-serif;line-height:18px;"> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　// Send the file "ftp_file.txt" to the for_jon directory.</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ftp_put("Ftp_Put",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　"SOURCE_PATH=f:/ftp_file.txt", "TARGET_PATH=/pub/for_jon", "MODE=ASCII",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ENDITEM ,</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　LAST);</p> </td> 
  </tr> 
 </tbody> 
</table>

兴匆匆地以为就行了，一运行又报错：

globals.h(101): Error -86025:Put failed; 550 /pub/for\_jon: Not a regular file

原来这次是TARGET\_PATH的问题，再看LR的帮助文档：

TARGET\_PATH (optional) - the path and filename in which to place the file.

if (M)SOURCE\_PATH is specified, but TARGET\_PATH is not specified, the file is stored in the root directory of the FTP server, with the original file name.

原来TARGET\_PATH要包含文件名，因此改成：

<table style="margin-left:0px;line-height:normal;border-right-color:rgb(153,153,153);border-right-width:1px;border-right-style:solid;border-top-color:rgb(153,153,153);border-top-width:1px;border-top-style:solid;font-size:12px;border-left-color:rgb(153,153,153);border-left-width:1px;border-left-style:solid;width:674px;border-bottom-color:rgb(153,153,153);border-bottom-width:1px;border-bottom-style:solid;font-family:'Courier new';background-color:rgb(221,221,221);"> 
 <tbody> 
  <tr> 
   <td style="margin-left:0px;font-size:12px;font-family:Verdana, '宋体', sans-serif;line-height:18px;"> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　// Send the file "ftp_file.txt" to the for_jon directory.</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ftp_put("Ftp_Put",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　"SOURCE_PATH=f:/ftp_file.txt", "TARGET_PATH=/pub/for_jon/ftp_file.txt", "MODE=ASCII",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ENDITEM ,</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　LAST);</p> </td> 
  </tr> 
 </tbody> 
</table>

这次终于行了。

同样的，在ftp\_put\_ex函数中也有类似的错误：

<table style="margin-left:0px;line-height:normal;border-right-color:rgb(153,153,153);border-right-width:1px;border-right-style:solid;border-top-color:rgb(153,153,153);border-top-width:1px;border-top-style:solid;font-size:12px;border-left-color:rgb(153,153,153);border-left-width:1px;border-left-style:solid;width:674px;border-bottom-color:rgb(153,153,153);border-bottom-width:1px;border-bottom-style:solid;font-family:'Courier new';background-color:rgb(221,221,221);"> 
 <tbody> 
  <tr> 
   <td style="margin-left:0px;font-size:12px;font-family:Verdana, '宋体', sans-serif;line-height:18px;"> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　In the following example, the ftp_get_ex function gets the file ftp_file.txt from the FTP server.</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　// Send the file "ftp_file.txt" to the for_jon directory.</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ftp_put_ex(&amp;ftp, "Ftp_Put",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　"PATH=f:/ftp_file.txt", "TARGET_PATH=/pub/for_jon", "MODE=ASCII",</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　ENDITEM,</p> <p style="margin-left:0px;border-top-width:0px;border-right-width:0px;border-bottom-width:0px;border-left-width:0px;list-style-type:none;line-height:18px;">　　LAST);</p> </td> 
  </tr> 
 </tbody> 
</table>

而且例子代码写的是“ftp\_put\_ex”， 描述例子时却说的是“ftp\_get\_ex”。

LR是非常优秀的性能测试工具，但是如果帮助文档中类似这样的错误比较多的话，对初学者而言就又多了一道学习的门槛：鉴别联机帮助信息的真伪的能力。