Arithmetic/Integer: Difference between revisions

The Unix shell does not directly support arithmetic operations , so external tools, such as ''expr'' are used to perform arithmetic calculations when required:

{{works with|Bourne shellShell}}

(Notes: Using the ` (backtick operators, also available in most Bourne shells via the ''$(...)'' syntax) allows us to keep the results on their labels in the most efficient and portable way. The spaces around the operators in the ''expr'' command line arguments are required and the shell requires us to quote or escape the ''*'' character has shown, to prevent any possible "globbing" --- filename expansion of the ''*'' as a wildcard character.

echo "a+b = $(($a+$b))"

echo "a-b = $(($a-$b))"

echo "a*b = $(($a*$b))"

echo "a/b = $(($a/$b))" # truncates towards 0

echo "a mod b = $(($a%$b))" # same sign as first operand</lang>

(Note: spaces inside the ''$((...))'' are optional and not required; the ''$((...))'' expressions can be inside or outside the double quotes, but the `...` expressions couldfrom alsothe haveprevious beenexample enclosedcan inalso thebe doubleinside quotesor inoutside the previousdouble example)quotes.