Arithmetic expressions - declare -i foo=[arith]

Arithmetic expressions are used in several situations:

* arithmetic evaluation command * arithmetic expansion * substring parameter expansion * the ''let'' builtin command * C-style for loop * array indexing * conditional expressions * Assignment statements, and arguments to declaration commands of variables with the integer attribute.

Arithmetic expressions are used in several situations:

* arithmetic evaluation command * arithmetic expansion * substring parameter expansion * the ''let'' builtin command * C-style for loop * array indexing * conditional expressions

$(( ))

$[ ]

The arithmetic expression is evaluated and expands to the result. The output of the arithmetic expansion is guaranteed to be one word and a digit in Bash.

Please do not use the second form $[ ... ]! It's deprecated. The preferred and standardized form is $(( ... ))!

$(( ))

$[ ]

The arithmetic expression is evaluated and the resulting value replaces the whole $((...)) construct:

Please do not use the second form $[ ... ]! It's deprecated. The preferred and standardized form is $(( ... ))!

Synopsis

let

Description

The let builtin command evaluates the arithmetic expression and returns the exit codes

* 0 (TRUE) when evaluated to not 0 (arithmetic "true") * 1 (FALSE) when evaluated to 0 (arithmetic "false")

Synopsis

let arg [arg ...]

Description

The let builtin command evaluates each supplied word from left to right as an arithmetic expression and returns an exit code according to the truth value of the rightmost expression.

* 0 (TRUE) when arg evaluated to not 0 (arithmetic "true") * 1 (FALSE) when arg evaluated to 0 (arithmetic "false")

PHP arithmetic operators Today we will lear about aritmetic operators for PHP. These are the arithmetic operators, below also a simple example, using the sum operator, to perform a simple sum of three numbers. <!--break-->

( )

This only works on systems that support named pipes (FIFO - a special file) or the /dev/fd/NNNNN-syntax to access open files.

Process substitution is performed simultaneously with parameter expansion, command substitution and arithmetic expansion.

I want to accumulate the line size of a number of files contained in a folder. I have written the following script:

let a=0 let num=0 for i in folder/* do num=`cat $i | wc -l` a=$a+$num done echo $a

What i am geting at the end of the script is 123+234+432+... and not the result of the arithmetic operation of addition.