IBM® Informix® Client Software Development Kit, Version 4.10
The string data type
The string data type is the IBM® Informix® ESQL/C data type that holds character data that is null terminated and does not contain trailing blanks.
However, if a string of blanks (that is, ‘ ’) is stored in a database field and selected into a host variable of the string data type, the result is a single blank character.
When an application reads a value from a CHAR column into a host variable of the string data type, it strips the value of any trailing blanks and appends a null terminator. The behavior is the same if an application reads a value from a VARCHAR column into a host variable of the string data type.
The one exception to this rule is that if the BLANK_STRINGS_NOT_NULL environment
variable is set to 1 or any other value, like 0 or 2, the string host
variable stores an empty string as a single blank followed by a null
terminator. If this environment variable is not set, string host variables
store an empty string as a null string.
EXEC SQL BEGIN DECLARE SECTION;
string buffer[16];
EXEC SQL END DECLARE SECTION;
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EXEC SQL select lname into :buffer from customer
where customer_num = 102;Declare the string data type with a length of [n +
1] (where n is the size of the column with values
that you want read) to allow for the null terminator. In the preceding
code fragment, the lname column in the customer table
is 15 bytes so the buffer host variable is declared as 16 bytes.
Use the following syntax to declare a host variable of the string data
type:
EXEC SQL BEGIN DECLARE SECTION;
string str_name[n + 1];
EXEC SQL END DECLARE SECTION;