18.4.1 Assignment

The assignment operation in the AIT language assigns the value of the right operand to the left operand. In assignment, you cannot use any constant as the left operand.

Organization of this subsection

(1) Format
(2) Description
(3) Example of coding

(1) Format

Assignment statement

assignment_expression END_STMT

Assignment expression

identifier assign_operand expression

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(2) Description

In assignment, the value of the right operand is stored in the left operand. The left operand must neither be a function nor be a constant.

If the data type of the right operand differs from that of the left operand, type conversion is performed when possible. This type conversion depends on the specified operator, and the type of operator or operand.

The following table lists the results of type conversion in the AIT language. Warning messages and errors for data conversion are displayed upon syntax checks.

Left operand	Right operand	Result	Description
`integer`	`integer`	`integer`	The value of one `integer`-type variable is assigned to the other `integer`-type variable.
`integer`	`float`	`integer`	The truncated value is assigned to the `integer`-type variable. A warning message is displayed because the data may become inaccurate.
`integer`	`bool`	`integer`	The value `true` is assigned to the `integer`-type variable as `1`. The value `false` is assigned to the `integer`-type variable as `0`.
`integer`	`string`	Error	Since the `string` type cannot be converted to the `integer` type, an error message is displayed.
`float`	`integer`	`float`	The value of the `integer`-type variable is assigned to the `float`-type variable.
`float`	`float`	`float`	The value of one `float`-type variable is assigned to the other `float`-type variable.
`float`	`bool`	`float`	The value `true` is assigned to the `float`-type variable as `1`. The value `false` is assigned to the `float`-type variable as `0`.
`float`	`string`	Error	Since the `string` type cannot be converted to the `float` type, an error message is displayed.
`bool`	`integer`	`bool`	A non-0 value is assigned to the `bool`-type variable as `true`. 0 is assigned to the `bool`-type variable as `false`. Since the original data is lost, a warning message is displayed.
`bool`	`float`	`bool`
`bool`	`bool`	`bool`	The value of one `bool`-type variable is assigned to the other `bool`-type variable.
`bool`	`string`	Error	Since the `string` type cannot be converted to the `bool` type, an error message is displayed.
`string`	`integer`	Error	Since the `integer` type cannot be converted to the `string` type, an error message is displayed.
`string`	`float`	Error	Since the `float` type cannot be converted to the `string` type, an error message is displayed.
`string`	`bool`	Error	Since the `bool` type cannot be converted to the `string` type, an error message is displayed.
`string`	`string`	`string`	The value of one `string`-type variable is assigned to the other `string`-type variable

The AIT language supports multi-assignment. The multi-assignment here means assignment of a value to two variables.

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(3) Example of coding

MAIN
    {
        a = 10;         // Value 10 is assigned to a.
        a = b = 20;     // Multi-assignment is coded.
                        // Value 20 is assigned to variable b,
                        // then to variable a.
    }

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