Duplicate Character Counter in Every Language

Welcome to the Duplicate Character Counter page! Here, you'll find a description of the project as well as a list of sample programs written in various languages.

Description

Although a one line solution for this problem is feasible, just as huge brute force solutions are, we should avoid both of these approaches. Instead, our goal should be to find a fine line between both, where the code is not bogged down but is largely readable and maintainable.

Requirements

The code should return the count of all duplicate, case-sensitive, alphanumeric characters, that occur more than once in the given string. Characters should also be presented in the order in which they appear in the string. For instance, 'abba' should output 'a' as the first character that has a duplicate.

Testing

Every project in the Sample Programs repo should be tested. In this section, we specify the set of tests specific to Duplicate Character Counter. In order to keep things simple, we split up the testing as follows:

• Duplicate Character Counter Valid Tests
• Duplicate Character Counter Invalid Tests

Duplicate Character Counter Valid Tests

Description	Input	Output
Sample Input: No Duplicates	"hola"	"No duplicate characters"
Sample Input: Routine	"goodbyeblues"	"o: 2" "b: 2" "e: 2"

Duplicate Character Counter Invalid Tests

Description	Input
No Input
Empty Input	""

All of these tests should output the following:

Usage: please provide a string

Articles

• Duplicate Character Counter in Algol68
• Duplicate Character Counter in C
• Duplicate Character Counter in C++
• Duplicate Character Counter in Euphoria
• Duplicate Character Counter in Java
• Duplicate Character Counter in Mathematica
• Duplicate Character Counter in Php
• Duplicate Character Counter in Python
• Duplicate Character Counter in Rust

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