AWK variables and data types

AWK provides several built-in variables for use in programs, as well as the ability to define and use user-defined variables. Here are some common AWK variables and data types:

– Built-in variables: AWK provides several built-in variables that can be used in programs. Some of the most commonly used ones include:

– `$0`: The entire line of input
– `$1`, `$2`, `$3`, etc.: The first, second, third, etc. fields of the input line, separated by a delimiter (by default, whitespace)
– `NF`: The number of fields in the input line
– `NR`: The current record or line number
– `FILENAME`: The name of the current input file being processed

– User-defined variables: AWK also allows you to define and use your own variables. Variables in AWK are dynamically typed, meaning that their data type is determined at runtime based on the value assigned to them. Here is an example of defining and using a variable in AWK:

`
  awk 'BEGIN { x = 5; print x * 2 }'
  

In this example, we define a variable `x` with a value of `5`, and then print the result of multiplying it by `2`.

– Data types: AWK supports the following data types:

– Numeric: AWK supports both integer and floating-point numbers. Numeric values can be assigned to variables using the standardassignment operator (`=`). For example:

    x = 10      # integer
    y = 3.14    # floating-point
    

– String: AWK supports strings as a data type, which can be enclosed in single or double quotes. For example:

    s1 = "hello"
    s2 = 'world'
    

– Array: Arrays are a composite data type in AWK, which can hold multiple values indexed by a key. Array elements can be accessed and modified using the index and assignment operator. For example:

    a[1] = "apple"
    a[2] = "banana"
    print a[1], a[2]   # prints "apple banana"
    

– Boolean: AWK supports boolean values, which are either true or false. Boolean values are typically used in conditional statements and comparisons. For example:

    x = 10
    y = 5
    if (x > y) {
        print "x is greater than y"
    } else {
        print "y is greater than x"
    }
    

In addition to these basic data types, AWK also provides some advanced data structures and functions, such as regular expressions, associative arrays, and built-in string manipulation functions.