Reverse String - Eiffel Typing CST Test

Mode:

Duration:

class
	REVERSE_STRING
feature
	reverse (s: STRING)
		local i: INTEGER; result: STRING
		do
		create result.make_empty
		from i := s.count until i = 0 loop
		result.append_character(s[i])
		i := i - 1
		end
		io.put_string(result); io.put_new_line
		end
end

! Run
local
	r: REVERSE_STRING
	s: STRING
do
	create r
	s := "Hello"
	r.reverse(s)
endCoding works best on desktop or with an external keyboard.

Reverse String — Eiffel Code

Reverses a string.

class
	REVERSE_STRING
feature
	reverse (s: STRING)
		local i: INTEGER; result: STRING
		do
		create result.make_empty
		from i := s.count until i = 0 loop
		result.append_character(s[i])
		i := i - 1
		end
		io.put_string(result); io.put_new_line
		end
end

! Run
local
	r: REVERSE_STRING
	s: STRING
do
	create r
	s := "Hello"
	r.reverse(s)
end

Eiffel Language Guide

Eiffel is a high-level, object-oriented programming language designed for software engineering with a strong emphasis on correctness, reusability, and maintainability. It supports the Design by Contract methodology, promoting robust and reliable applications.

Primary Use Cases

▸High-reliability enterprise software
▸Safety-critical systems
▸Reusable component libraries
▸Formal software engineering projects
▸Educational use for software engineering principles

Notable Features

▸Design by Contract
▸Strong static typing
▸Generic classes and collections
▸Multiple inheritance with controlled resolution
▸Automatic memory management (garbage collection)

Origin & Creator

Eiffel was created by Bertrand Meyer in the late 1980s at ETH Zurich and later developed further at Interactive Software Engineering.

Industrial Note

Eiffel is used in safety-critical systems, mission-critical enterprise applications, embedded systems requiring high reliability, and software frameworks emphasizing correctness.

Quick Explain

▸Eiffel enforces object-oriented principles such as classes, inheritance, polymorphism, and genericity.
▸Design by Contract allows developers to specify preconditions, postconditions, and invariants for software correctness.
▸Used for building complex systems, safety-critical applications, and reusable libraries.

Core Features

▸Classes, objects, and inheritance
▸Preconditions, postconditions, invariants
▸Genericity for reusable components
▸Deferred (abstract) and effective (concrete) classes
▸Exception handling and assertions

Learning Path

▸Learn basic OO principles
▸Understand Eiffel syntax and class structure
▸Master Design by Contract methodology
▸Practice with EiffelStudio IDE
▸Build reusable components and libraries

Practical Examples

▸Bank account management system with contracts
▸Inventory management with inheritance
▸Reusable generic container library
▸GUI applications using EiffelVision
▸Safety-critical simulation modules

Comparisons

▸Higher emphasis on correctness than Java or C++
▸Integrated contract system vs external testing
▸Object-oriented like C++ or Java, but with design-by-contract
▸Less widespread than mainstream languages
▸Focus on software engineering rigor

Strengths

▸Encourages correct and maintainable code
▸Supports formal software engineering methodologies
▸Highly reusable libraries via genericity
▸Robust exception handling and error detection
▸Object-oriented features fully integrated with contract-based programming

Limitations

▸Smaller developer community compared to mainstream languages
▸Limited third-party libraries and ecosystem
▸Less industry adoption for modern web/mobile applications
▸Verbose syntax for simple tasks
▸Learning curve for Design by Contract concepts

When NOT to Use

▸Small scripting tasks
▸Modern mobile app development
▸Rapid prototyping for web
▸Highly dynamic or loosely typed systems
▸Projects with tight integration with mainstream ecosystems without Eiffel libraries

Cheat Sheet

▸class ACCOUNT
▸feature
▸deposit(amount: REAL)
▸require amount > 0
▸ensure balance = old balance + amount

FAQ

▸Is Eiffel still relevant?
▸Yes - for software engineering and high-reliability systems.
▸Can Eiffel integrate with other languages?
▸Yes - C/C++, COM, .NET, and web services.
▸Does Eiffel support OO fully?
▸Yes - classes, inheritance, polymorphism, and generics are all supported.
▸What is Design by Contract?
▸A methodology to enforce correctness via preconditions, postconditions, and invariants.

30-Day Skill Plan

▸Week 1: Basic classes and objects
▸Week 2: Contracts and assertions
▸Week 3: Inheritance and polymorphism
▸Week 4: Generic classes and reusable libraries

Final Summary

▸Eiffel is a rigorously designed OO language for correctness, maintainability, and reusability.
▸Its Design by Contract methodology enforces reliability in software systems.
▸Used in high-reliability, enterprise, and safety-critical applications.
▸Less mainstream but highly valued for software engineering best practices.

Project Structure

▸Class files (.e)
▸Library or module folders
▸Project configuration files
▸Generated binaries or executable
▸Documentation and contract specifications

Monetization

▸Enterprise software development
▸Safety-critical application contracts
▸Consulting for reliable system design
▸Reusable library distribution
▸Educational and academic usage

Productivity Tips

▸Leverage EiffelStudio templates
▸Reuse generic classes
▸Write contracts for all critical features
▸Use unit tests extensively
▸Document invariants and assumptions

Basic Concepts

▸Classes, objects, and references
▸Features (methods) and attributes
▸Preconditions, postconditions, invariants
▸Generic classes
▸Inheritance and polymorphism

Official Docs

▸EiffelStudio Documentation
▸Design by Contract Reference
▸Eiffel Language Standard

More Eiffel Typing Exercises

Eiffel Counter and Theme Toggle Eiffel Fibonacci Sequence Eiffel Factorial Calculator Eiffel Prime Checker Eiffel Sum of Array Eiffel Multiplication Table Eiffel Temperature Converter Eiffel Simple Alarm Simulation Eiffel Random Walk Simulation

Practice Other Languages

C React Python C++Rust TypeScript Kotlin PHP Java C#Ruby Mql Cql N1ql Cypher

class
REVERSE_STRING
feature
reverse (s: STRING)
local i: INTEGER; result: STRING
do
create result.make_empty
from i := s.count until i = 0 loop
result.append_character(s[i])
i := i - 1
end
io.put_string(result); io.put_new_line
end
end

! Run
local
r: REVERSE_STRING
s: STRING
do
create r
s := "Hello"
r.reverse(s)
end

Coding works best on desktop or with an external keyboard.

Reverse String — Eiffel Code

Reverses a string.

class REVERSE_STRING feature reverse (s: STRING) local i: INTEGER; result: STRING do create result.make_empty from i := s.count until i = 0 loop result.append_character(s[i]) i := i - 1 end io.put_string(result); io.put_new_line end end ! Run local r: REVERSE_STRING s: STRING do create r s := "Hello" r.reverse(s) end

Eiffel Language Guide

Primary Use Cases

▸High-reliability enterprise software
▸Safety-critical systems
▸Reusable component libraries
▸Formal software engineering projects
▸Educational use for software engineering principles

Notable Features

▸Design by Contract
▸Strong static typing
▸Generic classes and collections
▸Multiple inheritance with controlled resolution
▸Automatic memory management (garbage collection)

Origin & Creator

Eiffel was created by Bertrand Meyer in the late 1980s at ETH Zurich and later developed further at Interactive Software Engineering.

Industrial Note

Eiffel is used in safety-critical systems, mission-critical enterprise applications, embedded systems requiring high reliability, and software frameworks emphasizing correctness.