User-defined functions in AWK

In AWK, you can define your own functions to encapsulate reusable code and make your programs more modular and readable. Here is the syntax for defining a user-defined function:

function name(args) {
  # code to execute
  return value;
}

– `name` is the name of the function.
– `args` is a comma-separated list of arguments to the function.
– `# code to execute` is the code that the function executes when it is called.
– `return value` is an optional statement that returns a value from the function.

Here is an example of defining and using a user-defined function in AWK:

function square(x) {
  return x * x;
}

{ print square($1); }

In this example, we define a function `square` that takes one argument `x` and returns its square. We then use the function in the AWK program to print the square of the first field of each input line.

You can also define functions that take multiple arguments, process arrays, and perform complex operations. Here is an example of a function that takes an array as an argument and returns its sum:

function sum_array(arr) {
  sum = 0;
  for (i in arr) {
    sum += arr[i];
  }
  return sum;
}

{ 
  split($0, arr, " ");
  print sum_array(arr);
}

In this example, we definea function `sum_array` that takes an array `arr` as an argument, loops over its elements and returns their sum. We then use the function in the AWK program to split each input line into an array using the separator `” “`, and print the sum of the array.

You can also define functions that call other functions, use control structures, and perform more complex operations. Here is an example of a function that finds the maximum value of an array:

function max_array(arr) {
  max = arr[1];
  for (i in arr) {
    if (arr[i] > max) {
      max = arr[i];
    }
  }
  return max;
}

function square(x) {
  return x * x;
}

{ 
  split($0, arr, " ");
  for (i in arr) {
    arr[i] = square(arr[i]);
  }
  print max_array(arr);
}

In this example, we define a function `max_array` that takes an array `arr` as an argument, loops over its elements and finds the maximum value. We also define a function `square` that squares its argument. We then use both functions in the AWK program to split each input line into an array using the separator `” “`, square each element of the array using the `square` function, find the maximum value of the array using the `max_array` function, and print the result.

These are just afew examples of the user-defined functions that you can create in AWK. You can define functions that perform any operation that you need in your program, and use them to make your code more modular and reusable.