The mi_set_varlen() function

The mi_set_varlen() accessor routine sets the length of the data in a varying-length structure (such as mi_lvarchar).

Syntax

void mi_set_varlen(varlen_ptr, data_len)
   mi_lvarchar *varlen_ptr;
   mi_integer data_len;
varlen_ptr
A pointer to the varying-length structure.
data_len
The length of the data to store in the varying-length descriptor.
Valid in client LIBMI application? Valid in user-defined routine?
Yes Yes

Usage

The mi_set_varlen() function sets the data length to data_len in the varying-length structure that varlen_ptr references. Uses for mi_set_varlen() include:
  • Before a call to the mi_set_vardata() or mi_set_vardata_align() function to tell these functions how many bytes of data to store
  • When you set your own data portion with mi_set_varptr() to set the data length in a user-allocated data portion
Important: The varying-length structure that varlen_ptr references is an opaque structure. Do not access fields of this structure directly. Instead, use the mi_set_vardata() function to set the data length in this structure.

The mi_set_varlen() function sets the data length in the varying-length descriptor. If you specify a data length larger than the current data portion, this function does not reallocate the data portion. Therefore, when you change the data length with mi_set_varlen(), make sure that the new value does not exceed the size of the data portion.

The data in a varying-length structure is not null terminated. Make sure that you use mi_set_varlen() to set the length of the actual varying-length data, not including any null terminator.

Although the varlen_ptr argument is declared as a pointer to an mi_lvarchar value, you can also use the mi_set_varlen() function to set data length in other varying-length data types, such as mi_sendrecv.

For information about when to set the length of a varying-length structure, see the Informix® DataBlade® API Programmer's Guide.

Return values

None.