In LoadRunner, you can add C Vuser functions to any Vuser script in order to enhance the script. VuGen generates only a few of the general Vuser functions while you record. If required, the remaining functions can be manually programmed into a script.

As per my knowledge, below is a list of general API functions for ANSI C scripts. It includes all protocols except for Java, VB, and GUI:

Transaction Functions:

1. lr_end_sub_transaction --> Marks the end of a sub-transaction for performance analysis.

2. lr_end_transaction --> Marks the end of a transaction.

3. lr_end_transaction_instance --> Marks the end of a transaction instance for performance analysis.

4. lr_fail_trans_with_error --> Sets the status of open transactions to LR_FAIL and sends an error message.

5. lr_get_trans_instance_duration --> Gets the duration of a transaction instance specified by its handle.

6. lr_get_trans_instance_wasted_time --> Gets the wasted time of a transaction instance by its handle.

7. lr_get_transaction_duration --> Gets the duration of a transaction by its name.

8. lr_get_transaction_think_time --> Gets the think time of a transaction by its name.

9. lr_get_transaction_wasted_time --> Gets the wasted time of a transaction by its name.

10. lr_resume_transaction --> Resumes collecting transaction data for performance analysis.

11. lr_resume_transaction_instance --> Resumes collecting transaction instance data for performance analysis.

12. lr_set_transaction_instance_status --> Sets the status of a transaction instance.

13. lr_set_transaction_status --> Sets the status of open transactions.

14. lr_set_transaction_status_by_name --> Sets the status of a transaction.

15. lr_start_sub_transaction --> Marks the beginning of a subtransaction.

16. lr_start_transaction --> Marks the beginning of a transaction.

17. lr_start_transaction_instance --> Starts a nested transaction specified by its parent’s handle.

18. lr_stop_transaction --> Stops the collection of transaction data.

19. lr_stop_transaction_instance --> Stops collecting data for a transaction specified by its handle.

20. lr_wasted_time --> Removes wasted time from all open transactions.

Command Line Parsing Functions:

1. lr_get_attrib_double --> Retrieves a double type variable used on the script command line.

2. lr_get_attrib_long --> Retrieves a long type variable used on the script command line.

3. lr_get_attrib_string --> Retrieves a string used on the script command line.

Informational Functions:

1. lr_user_data_point --> Records a user-defined data sample.

2. lr_whoami --> Returns information about a Vuser to the Vuser script. Not applicable for Application Management.

3. lr_get_host_name --> Returns the name of the host executing the Vuser script.

4. lr_get_master_host_name --> Returns the name of the machine running the LoadRunner Controller or Tuning Console. Not applicable for Application Management.

String Functions:

1. lr_eval_string --> Replaces a parameter with its current value.

2. lr_save_string --> Saves a null-terminated string to a parameter.

3. lr_save_var --> Saves a variable length string to a parameter.

4. lr_save_datetime --> Saves the current date and time to a parameter.

5. lr _advance_param --> Advances to the next available parameter.

6. lr _decrypt --> Decrypts an encoded string.

7. lr_eval_string_ext --> Retrieves a pointer to a buffer containing parameter data.

8. lr_eval_string_ext_free --> Frees the pointer allocated by lr_eval_string_ext.

9. lr_save_searched_string --> Searches for an occurrence of string in a buffer and saves a portion of the buffer, relative to the string occurrence, to a parameter.

Message Functions:

1. lr_debug_message --> Sends a debug message to the Output window or the Business Process Monitor log files.

2. lr_error_message --> Sends an error message to the Output window or the Business Process Monitor log files.

3. lr_get_debug_message --> Retrieves the current message class.

4. lr_log_message --> Sends a message to a log file.

5. lr_output_message --> Sends a message to the Output window or the Business Process Monitor log files.

6. lr_set_debug_message --> Sets a debug message class.

7. lr_vuser_status_message --> Generates and prints formatted output to the Controller or Console Vuser status area. Not applicable for Application Management.

8. lr_message --> Sends a message to the Vuser log and Output window or the Business Process Monitor log files.

Run-Time Functions

1. lr_load_dll --> Loads an external DLL.

2. lr_peek_events --> Indicates where a Vuser script can be paused.

3. lr_think_time --> Pauses script execution to emulate think time—the time a real user pauses to think between actions.

4. lr_continue_on_error --> Specifies an error handling method.

5. lr_rendezvous --> Sets a rendezvous point in a Vuser script. Not applicable for Application Management.

Also See: Other LoadRunner Tutorials