# Operator - Foundation

Minus operator (unary): reverses sign of operand (multiplies operand by -1).

Minus operator (binary): numeric subtraction or string concatenation.

```
<nValue1> - <nValue2> // subtraction
<dDate1> - <dDate2> // subtraction
<dDate> - <nValue> // subtraction
<cString1> - <cString2> // string concatenation
```

The operations of the subtraction operator are dependent on the program context and on the data type of the operands:

When a unary subtraction operator precedes a numeric expression, it corresponds to a multiplication with the value -1. This changes the sign of the numeric value. This operation has precedence over all other numeric operations.

When the binary subtraction operator is used with two numeric expressions <nValue1> and <nValue2>, it subtracts the value of the right expression <nValue2> from the value of the left expression <nValue1>. The result of the subtraction is a numeric value which is the difference between the two expressions.

When the subtraction operator is used with two date expressions <dDate1> and <dDate2>, it subtracts the date of the right expression <dDate2> from the date of the left expression <dDate1>. The result of the subtraction is a numeric value which indicates the difference in number of days.

If the left operand of the subtraction operator is a date expression <dDate> and the right operand is a numeric expression <nValue>, the numeric number of days <nValue> is subtracted from the date <dDate>. The result is a date value. A runtime error is generated if the left operand is numeric and the right operand is of data type date.

When the binary subtraction operator is used with two character expressions <cString1> and <cString2>, the character string of the right expression is attached to the left expression <cString1>, after all blank spaces (Chr(32)) at the end of the left character expression are removed and placed at the end of the resulting character string.

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