Solved: reverse a string

Reversing strings is a commonly encountered problem in many programming fields. It may seem simple at first glance, but it can get quite tricky, especially when it starts affecting application performance. In this article, we will discuss how this problem can be solved using COBOL, providing a detailed step-by-step guide of the process.

A Solution to Reverse a String in COBOL

COBOL, short for COmmon Business-Oriented Language, is one of the oldest programming languages. Despite its age, the power and efficiency of COBOL for dealing with large volumes of data cannot be overlooked. With COBOL, reversing a string can be simply done using the inbuilt features of the language. An example of how it is done can be seen in the following sample:

PROGRAM-ID. principle.
01 my-string PIC X(50) VALUE ‘This is a string to reverse’.
01 reversed-string PIC X(50) VALUE SPACES.
01 index PIC 9(2) VALUE ZERO.
PERFORM VARYING index FROM 50 BY -1 UNTIL index = 0
STRING my-string(index:1) DELIMITED BY SIZE
INTO reversed-string
DISPLAY reversed-string

Step-by-Step Explanation of the Code

This simple program explores the process of reversing a string, character by character, starting from the last character. It is a good example of using the STRING statement in COBOL, which is designed for operations on strings.

The STRING statement concatenates two or more strings into one, removing any delimiters. In this case, it’s being used to produce a reverse string. The PERFORM VARYING operation is critical here. It starts the loop from the end of the string and gradually concatenates each character into the variable reversed-string.

COBOL Libraries and Functions for String Manipulation

COBOL does not have a typical library system like other modern languages such as Python or Java. However, it contains a certain set of in-built functionalities that can be utilized in string manipulation or any other data manipulations.

For instance, as seen in the above solution; the STRING and PERFORM VARYING operations can do a lot of powerful things with strings. Other operations like UNSTRING, INSPECT, and reference modification can also be equally beneficial in different scenarios.

  • As shown in the example, STRING is a powerful operation for concatenating strings. On the other hand, UNSTRING is its opposite and is used to split a string into parts.

  • This operation is used for several purposes including but not limited to scanning and replacing substrings within a string.

  • Reference Modification:
  • It is a unique feature of COBOL, and it allows programmers to select a substring from a string, which is quite handy during string manipulation.

    This article intended to highlight a basic yet essential string manipulation task in COBOL; reversing a string. With this step-by-step guide and the showcased COBOL capabilities, we hope you found clarity and understanding. Continue exploring and mastering such intricacies and become adept at problem-solving in COBOL!

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