[Everyday C# - 12] Strings: concatenate, modify, compare, interpolation tutorial

[BillWagner]

Pull three string how-tos into the Fundamentals common-tasks/ group, move the interpolation tutorial into fundamentals/tutorials/, and redistribute deep-dive material into the language-reference string-operations.md page that PR 11 introduced. Pattern mirrors PR 11 (#53991) exactly.

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📄 File	🔗 Preview link
docs/core/extensions/logging/library-guidance.md	Logging guidance for .NET library authors
docs/csharp/advanced-topics/update-applications/nullable-migration-strategies.md	Nullable migration strategies
docs/csharp/fundamentals/null-safety/common-tasks/resolve-warnings.md	Resolve nullable warnings
docs/csharp/fundamentals/null-safety/nullable-reference-types.md	Nullable reference types
docs/csharp/fundamentals/strings/common-tasks/compare.md	docs/csharp/fundamentals/strings/common-tasks/compare
docs/csharp/fundamentals/strings/common-tasks/concatenate.md	Concatenate strings in C#
docs/csharp/fundamentals/strings/common-tasks/modify.md	"Modify string contents in C#"
docs/csharp/fundamentals/strings/common-tasks/search.md	Search strings in C#
docs/csharp/fundamentals/strings/common-tasks/split.md	docs/csharp/fundamentals/strings/common-tasks/split
docs/csharp/fundamentals/strings/interpolation.md	String interpolation in C#
docs/csharp/fundamentals/tutorials/nullable-reference-types.md	Tutorial: Express your design intent with nullable and non-nullable reference types
docs/csharp/fundamentals/tutorials/string-interpolation.md	"Tutorial: Learn string interpolation"
docs/csharp/how-to/index.md	How to (C#)
docs/csharp/language-reference/builtin-types/string-operations.md	String operations: pattern matching, performance, and span-based search
docs/csharp/language-reference/operators/addition-operator.md	Addition operators - + and +=
docs/csharp/language-reference/operators/equality-operators.md	Equality operators - test if two objects are equal or not
docs/csharp/language-reference/toc.yml	docs/csharp/language-reference/toc
docs/csharp/language-reference/tokens/interpolated.md	String interpolation using $
docs/csharp/programming-guide/strings/index.md	"Strings"
docs/csharp/toc.yml	Taken from https://github.com/dotnet/roslyn/wiki/Samples-and-Walkthroughs
docs/framework/performance/performance-tips.md	docs/framework/performance/performance-tips
docs/fundamentals/code-analysis/quality-rules/ca1305.md	CA1305: Specify IFormatProvider
docs/standard/base-types/best-practices-strings.md	Best practices for comparing strings in .NET
docs/standard/base-types/divide-up-strings.md	Separate strings into substrings

[Copilot]

Pull request overview

This pull request continues the Everyday C# Fundamentals restructuring by moving the string “how-to” content into the Fundamentals > Strings > Common tasks area, relocating/refreshing the string interpolation tutorial, and adding a new language-reference page for deeper string operations content. It also updates TOCs, cross-links, and redirections to match the new information architecture.

Changes:

• Added new Fundamentals string articles (search, split, concatenate, modify, compare) and new snippet projects targeting net10.0.
• Added a new language-reference article for advanced string operations (regex, span-based search, and StringComparison) with supporting snippets.
• Updated TOCs, cross-references across docs, removed old how-to pages/snippets, and added/adjusted redirections.

Reviewed changes

Copilot reviewed 53 out of 56 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
docs/standard/base-types/divide-up-strings.md	Updates “See also” link to the new Fundamentals split article.
docs/standard/base-types/best-practices-strings.md	Updates “See also” link to the new Fundamentals compare article.
docs/fundamentals/code-analysis/quality-rules/ca1305.md	Updates interpolation tutorial link to the new location.
docs/framework/performance/performance-tips.md	Updates concatenation guidance link to the new Fundamentals concatenate article.
docs/csharp/toc.yml	Reorganizes Strings and Null safety nav, adds new pages, and relocates the interpolation tutorial entry.
docs/csharp/programming-guide/strings/index.md	Repoints related-articles links to the new Fundamentals string common tasks pages and tutorial location.
docs/csharp/language-reference/tokens/interpolated.md	Updates “new to interpolation” tutorial link to the new Fundamentals tutorial path.
docs/csharp/language-reference/toc.yml	Adds new language-reference entry for “String operations”.
docs/csharp/language-reference/operators/equality-operators.md	Updates compare-strings link to the new Fundamentals compare article.
docs/csharp/language-reference/operators/addition-operator.md	Updates concatenate link to the new Fundamentals concatenate article.
docs/csharp/language-reference/builtin-types/string-operations.md	Introduces a new language-reference deep-dive page for advanced string operations.
docs/csharp/language-reference/builtin-types/snippets/string-operations/string-operations.csproj	Adds a new net10.0 snippet project for the language-reference article.
docs/csharp/language-reference/builtin-types/snippets/string-operations/Program.cs	Adds executable snippets for regex, span search, comparisons, and string.Create.
docs/csharp/how-to/snippets/strings/strings.csproj	Removes the old consolidated how-to snippet project.
docs/csharp/how-to/snippets/strings/SearchStrings.cs	Removes the old how-to search snippets (content migrated).
docs/csharp/how-to/snippets/strings/Program.cs	Removes the old how-to snippet runner.
docs/csharp/how-to/snippets/strings/ParseStringsUsingSplit.cs	Removes the old how-to split snippets (content migrated).
docs/csharp/how-to/snippets/strings/ModifyStrings.cs	Removes the old how-to modify snippets (content migrated).
docs/csharp/how-to/snippets/strings/Concatenate.cs	Removes the old how-to concatenate snippets (content migrated).
docs/csharp/how-to/snippets/strings/CompareStrings.cs	Removes the old how-to compare snippets (content migrated).
docs/csharp/how-to/search-strings.md	Removes the old how-to article (replaced by Fundamentals common task + language reference).
docs/csharp/how-to/parse-strings-using-split.md	Removes the old how-to article (replaced by Fundamentals common task).
docs/csharp/how-to/modify-string-contents.md	Removes the old how-to article (replaced by Fundamentals common task).
docs/csharp/how-to/index.md	Updates the how-to landing page links to point at the new Fundamentals common task pages.
docs/csharp/how-to/concatenate-multiple-strings.md	Removes the old how-to article (replaced by Fundamentals common task).
docs/csharp/how-to/compare-strings.md	Removes the old how-to article (replaced by Fundamentals common task).
docs/csharp/fundamentals/tutorials/string-interpolation.md	Updates and relocates the interpolation tutorial (new frontmatter, paths, and snippet references).
docs/csharp/fundamentals/tutorials/snippets/string-interpolation/string-interpolation.csproj	Updates tutorial snippet project to net10.0.
docs/csharp/fundamentals/tutorials/snippets/string-interpolation/Program.cs	Refreshes tutorial snippet code (modern syntax and additional alignment call).
docs/csharp/fundamentals/tutorials/nullable-reference-types.md	Updates related-content link to the new resolve-warnings location.
docs/csharp/fundamentals/strings/snippets/interpolation/Program.cs	Adds a new Fundamentals “strings/interpolation” snippet set.
docs/csharp/fundamentals/strings/snippets/interpolation/interpolation.csproj	Adds a new net10.0 snippet project for Fundamentals string interpolation article.
docs/csharp/fundamentals/strings/interpolation.md	Adds a new Fundamentals string interpolation concept article.
docs/csharp/fundamentals/strings/common-tasks/split.md	Adds new Fundamentals split article referencing new snippets.
docs/csharp/fundamentals/strings/common-tasks/snippets/split/split.csproj	Adds a new net10.0 snippet project for split common task.
docs/csharp/fundamentals/strings/common-tasks/snippets/split/Program.cs	Adds updated split examples as executable snippets.
docs/csharp/fundamentals/strings/common-tasks/snippets/search/search.csproj	Adds a new net10.0 snippet project for search common task.
docs/csharp/fundamentals/strings/common-tasks/snippets/search/Program.cs	Adds updated search examples as executable snippets.
docs/csharp/fundamentals/strings/common-tasks/snippets/modify/Program.cs	Adds updated modify examples as executable snippets.
docs/csharp/fundamentals/strings/common-tasks/snippets/modify/modify.csproj	Adds a new net10.0 snippet project for modify common task.
docs/csharp/fundamentals/strings/common-tasks/snippets/concatenate/Program.cs	Adds updated concatenate examples as executable snippets.
docs/csharp/fundamentals/strings/common-tasks/snippets/concatenate/concatenate.csproj	Adds a new net10.0 snippet project for concatenate common task.
docs/csharp/fundamentals/strings/common-tasks/snippets/compare/Program.cs	Adds updated compare examples as executable snippets.
docs/csharp/fundamentals/strings/common-tasks/snippets/compare/compare.csproj	Adds a new net10.0 snippet project for compare common task.
docs/csharp/fundamentals/strings/common-tasks/search.md	Adds new Fundamentals search article referencing new snippets.
docs/csharp/fundamentals/strings/common-tasks/modify.md	Adds new Fundamentals modify article referencing new snippets.
docs/csharp/fundamentals/strings/common-tasks/concatenate.md	Adds new Fundamentals concatenate article referencing new snippets.
docs/csharp/fundamentals/strings/common-tasks/compare.md	Adds new Fundamentals compare article referencing new snippets.
docs/csharp/fundamentals/null-safety/nullable-reference-types.md	Updates link to resolve-warnings after moving it under common tasks.
docs/csharp/fundamentals/null-safety/common-tasks/snippets/resolve-warnings/resolve-warnings.csproj	Adds a new net10.0 snippet project for resolve-warnings.
docs/csharp/fundamentals/null-safety/common-tasks/snippets/resolve-warnings/project-snippet.xml	Adds a small project snippet used by the resolve-warnings article.
docs/csharp/fundamentals/null-safety/common-tasks/snippets/resolve-warnings/Program.cs	Adds executable examples for common nullable warning patterns and fixes.
docs/csharp/fundamentals/null-safety/common-tasks/resolve-warnings.md	Fixes relative links after the resolve-warnings move to common-tasks/.
docs/csharp/advanced-topics/update-applications/nullable-migration-strategies.md	Updates links to resolve-warnings after the new common-tasks/ location.
docs/core/extensions/logging/library-guidance.md	Updates string interpolation tutorial link to the new Fundamentals tutorial path.
.openpublishing.redirection.csharp.json	Adds/adjusts redirections for moved/deleted pages.