How can I compare two strings in AWK and find their location index?

In AWK, you can compare two strings using standard comparison operators (==, !=, <, >, <=, >=). To find the location index of a substring within a string, you can use the index() function.

Here’s how you can achieve both comparison and index finding:

String Comparison:

AWK allows you to compare strings lexicographically, meaning it compares them based on character-by-character ordering. For equality checks, use ==, and for inequality use !=. Comparison for greater than/less than uses the standard <, >, <= and >= operators.

Example:

BEGIN {
  str1 = "hello";
  str2 = "world";
  str3 = "hello";

  if (str1 == str3) {
    print "str1 and str3 are equal";
  }
  if (str1 != str2) {
    print "str1 and str2 are not equal";
  }
  if (str1 < str2) {
    print "str1 is less than str2";
  }
}

Finding the Index of a Substring:

The index(str, substr) function in AWK returns the starting position (1-based index) of the substring substr within the string str. If substr is not found, it returns 0.

Example:

BEGIN {
  str = "hello world";
  substr = "world";
  location = index(str, substr);
  if (location != 0) {
    print "Substring '" substr "' found at index: " location;
  } else {
    print "Substring '" substr "' not found";
  }

  substr2 = "test";
  location2 = index(str, substr2);
  if (location2 != 0) {
    print "Substring '" substr2 "' found at index: " location2;
  } else {
    print "Substring '" substr2 "' not found";
  }
}

Combining Comparison and Index Finding:

You can combine these techniques to perform conditional logic based on both comparisons and substring locations. For example, you might check if a string contains a specific pattern and then perform further actions accordingly.

BEGIN {
  str = "This is a sample string";
  substr = "sample";

  if(index(str, substr) != 0) {
    print "The string '" str "' contains the substring '" substr "'";
     location = index(str, substr);
     print "The index of substring is " location;
   } else {
     print "The string '" str "' does not contain the substring '" substr "'";
  }
}

By using ==, != for string comparisons and the index() function for substring location, you can effectively manage and analyze strings within your AWK scripts.

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