Enters a value in the table, which was created by sf_simtab_init. In the input it must be told which table to enter the value in, this is the first input argument and is of type sf_simtab. The second and the third arguments are the pointers of const char* type. The first one points to key, which would be the name of the argument from command line or file. Second argument is the pointer to the value to be input.