Creating dll files and using it in LoadRunner scripts

Creating DLLs have tons of advantage, especially when you want to take your scripts away from the beaten path. I won’t blabber much in this post and would like to take you people right into the topic I want to cover.

In the previous post I mentioned about Search And Replace function. To serve the purpose of an example, I have recreated the same Search And Replace function in VC++(2010) expresss edition and built a DLL file.

Below is the code that created in VC++:

#include "stdafx.h"
#include "C:\Program Files\HP\LoadRunner\include\lrun.h"

extern "C" __declspec( dllexport ) int lr_searchReplace(char* inputStr, char* outputStr, char lookupChar, char repChar);

int lr_searchReplace(char* inputStr, char* outputStr, char lookupChar, char repChar)
{

char *ptr =inputStr;
char xchar;
int len=0;
int i=0;

lr_output_message("%s",inputStr);
xchar = *ptr;//Copy initial
len=strlen(inputStr);
while (len>0)
{

len--;
xchar = *ptr;
if(xchar==' ')
{
inputStr[i]= repChar;

}

ptr++;
i++;

}

lr_save_string(inputStr,outputStr);
lr_output_message("%s",inputStr);

return 0;
}


Before attempting to build this dll project in VC++, ensure that you have included lrun50.lib in the aditional linker file settings which is in Project Options, else the project won't successfully build/compile. lrun.lib should be present inside \lib folder. Also make sure you include the lrun.h header file as shown in the above code snippet.

After the project is built, dig into the debug folder to find the dll file and then copy it inside the LoadRunner script folder and use it as shown below:

Action()
{
lr_load_dll("SearchNReplace.dll");
lr_save_string("this is a dummy text", "cProjectName");
r_searchReplace(lr_eval_string("{cProjectName}"), "convProjName", ' ', '+');
lr_output_message("%s",lr_eval_string("{convProjName}"));
return 0;
}