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Implicit Conversion

Implicit conversion occurs when operands of differing types are acted upon by an operator. During assignment, the result of the operand on the right will always be implicitly converted to the type of operand on the left of the assignment operator. This table outlines the conversion rules that occur in operations other than assignments:

Expression operands	Implicit conversion of operands	Internal result type
STRING op INTEGER	STRING op STRING	STRING
STRING op DECIMAL	STRING op STRING	STRING
STRING op STRING	STRING op STRING	STRING
INTEGER op INTEGER	INTEGER op INTEGER	*INTEGER DECIMAL
INTEGER op DECIMAL	DECIMAL op DECIMAL	DECIMAL
INTEGER op STRING	INTEGER op INTEGER or **DECIMAL op DECIMAL	INTEGER DECIMAL
DECIMAL op INTEGER	DECIMAL op DECIMAL	DECIMAL
DECIMAL op DECIMAL	DECIMAL op DECIMAL	DECIMAL
DECIMAL op STRING	DECIMAL op DECIMAL	DECIMAL
* The result of division between INTEGER data types is always a DECIMAL. ** When a string requires conversion to a numeric value it is converted to a DECIMAL data type if it contains a valid decimal value otherwise, it is converted to an INTEGER data type. The resulting type then determines which implicit conversion rules apply.

Here is an example:

#val=$temp

The value of $temp is converted (internally) to an integer because the assignment is to an integer. During this implicit conversion, the actual value contained in $temp is not changed. If $temp has a value of 10.25 before executing this statement, #val would now have a value of 10.25, and $temp would still be 10.25.

Note

Operands of differing types can be assigned to each other, but this does not mean that the two operands will be equal after such assignment.

In this example...

#val="January"

the string constant would be converted to an INTEGER before assignment. Since the string constant does not contain a valid number, the value of #val will be zero (0) after execution of this statement.

In this example...

$temp= 10/6

the constants 10 and 6 are of type INTEGER because they have no decimal value indicated. The resulting internal calculation will be a DECIMAL because the act of division always results in a DECIMAL value. Therefore, the value of $temp after the evaluation will be 1.66667. To assign the integer result of division into a DECIMAL data type, it will be necessary to first assign the result into an INTEGER data type, or to use the expression as the parameter to the INT built-in function.

Here is an example of implicit conversion differences:

TEXT="001";

IF (TEXT=1);

TEMP1="YES";

ELSE;

TEMP1="NO";

END;

IF(1=TEXT);

TEMP2="YES";

ELSE;

TEMP2="NO";

END

After executing these statements, TEMP1 will contain NO and TEMP2 will contain YES.

In the first IF statement, the expression (TEXT=1) compares a string with an integer. According to the rules of implicit conversion, the integer is first converted into a string and then the two objects are evaluated according to the operator. When comparing strings, 001 does not equal 1.

In the second IF statement, the expression (1=TEXT) compares an integer to a string. Implicit conversion will change the string into an integer before performing the operation. The converted expression can be represented as (1=1), which are equal

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