The `awk`

language uses the common arithmetic operators when
evaluating expressions. All of these arithmetic operators follow normal
precedence rules, and work as you would expect them to.

Here is a file ``grades'` containing a list of student names and
three test scores per student (it's a small class):

Pat 100 97 58 Sandy 84 72 93 Chris 72 92 89

This programs takes the file ``grades'`, and prints the average
of the scores.

$ awk '{ sum = $2 + $3 + $4 ; avg = sum / 3 > print $1, avg }' grades -| Pat 85 -| Sandy 83 -| Chris 84.3333

This table lists the arithmetic operators in `awk`

, in order from
highest precedence to lowest:

`-`

`x`- Negation.
`+`

`x`- Unary plus. The expression is converted to a number.
`x`^`y``x`**`y`-
Exponentiation:
`x`raised to the`y`power.``2 ^ 3'`has the value eight. The character sequence``**'`is equivalent to``^'`. (The POSIX standard only specifies the use of``^'`for exponentiation.) `x`*`y`- Multiplication.
`x`/`y`-
Division. Since all numbers in
`awk`

are real numbers, the result is not rounded to an integer:``3 / 4'`has the value 0.75. `x`%`y`-
Remainder. The quotient is rounded toward zero to an integer,
multiplied by
`y`and this result is subtracted from`x`. This operation is sometimes known as "trunc-mod." The following relation always holds:b * int(a / b) + (a % b) == a

One possibly undesirable effect of this definition of remainder is that

is negative if`x`%`y``x`is negative. Thus,-17 % 8 = -1

In other`awk`

implementations, the signedness of the remainder may be machine dependent. `x`+`y`- Addition.
`x`-`y`- Subtraction.

For maximum portability, do not use the ``**'` operator.

Unary plus and minus have the same precedence, the multiplication operators all have the same precedence, and addition and subtraction have the same precedence.

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