Program to Increment the parameter when the parameter has more digits

I have a Parameter. I want to increase the parameter value by 1.

Below is the code to capture the parameter and increment it by 1.

Action()

{
long double i;   
lr_save_string("1234567899", "id");
i = atol(lr_eval_string("{id}"));
i =i+1;   
lr_save_int(i, "id");
lr_output_message("Value is: %s", lr_eval_string("{id}"));
return 0;

}

Output:

Starting action Action.

Action.c(12): Value is: 1234567900

Ending action Action.

Ending Vuser...

If we increase the Length of parameter by one more digit (here 11 digits).  The below logic fails as shown below. L L

Action()
{
long double i;   
lr_save_string("12345678999", "id");
i = atol(lr_eval_string("{id}"));
i =i+1;   
lr_save_int(i, "id");
lr_output_message("Value is: %s", lr_eval_string("{id}"));
return 0;
}

Starting action Action.

Action.c(12): Value is: -2147483648

Ending action Action.

So, the solution to handle this type of issues is as below:

Action()
{
   
char *ptr, *id;
   
lr_save_string("1234567890123499999", "id");

id = lr_eval_string("{id}"); 

ptr =id+strlen(id)-1;

lr_output_message("value of ptr = %s", ptr );

lr_output_message("Original value = %s", id );

/* While Loop to continue adding if digit is 9 */
while (++*ptr > '9')
{
    *ptr-- = '0';
}

lr_output_message("Incremented value = %s", id);

return 0;
}

Output:

Starting action Action.

Action.c(12): value of ptr = 9

Action.c(14): Original value = 1234567890123499999

Action.c(22): Incremented value = 1234567890123500000

Ending action Action.