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Learning Perl, Second Edition by Randal L. Schwartz, Tom Christiansen

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2.4. Scalar Operators

An operator produces a new value (the result) from one or more other values (the operands). For example, + is an operator because it takes two numbers (the operands, like 5 and 6), and produces a new value (11, the result).

Perl's operators and expressions are generally a superset of those provided in most other ALGOL/Pascal-like programming languages, such as C or Java. An operator expects either numeric or string operands (or possibly a combination of both). If you provide a string operand where a number is expected, or vice versa, Perl automatically converts the operand using fairly intuitive rules, which will be detailed in Section 2.4.4, below.

2.4.1. Operators for Numbers

Perl provides the typical ordinary addition, subtraction, multiplication, and division operators, and so on. For example:

2 + 3     # 2 plus 3, or 5
5.1 - 2.4 # 5.1 minus 2.4, or approximately 2.7
3 * 12    # 3 times 12 = 36
14 / 2    # 14 divided by 2, or 7
10.2 / 0.3 # 10.2 divided by 0.3, or approximately 34
10 / 3    # always floating point divide, so approximately 3.3333333...

Additionally, Perl provides the FORTRAN-like exponentiation operator, which many have yearned for in Pascal and C. The operator is represented by the double asterisk, such as 2**3, which is two to the third power, or eight. (If the result can't fit into a double-precision floating-point number, such as a negative number to a noninteger exponent, or a large number to a large exponent, you'll get a fatal error.) ...

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