Fmt
fmt is a software library or package that provides formatted text generation and, in some implementations, formatted input and output operations.
Go in Action, Second Edition
The fmt package is a Go standard-library package that provides formatted input and output operations.
- How it is used
- Handles console output, formatted string construction, simple input, and basic error reporting in Go applications.
- How deep it goes
- Explains core printing, formatting verbs, string builders, input, and formatted errors, while deferring advanced logging options.
- Examples
- Uses word-count output, a versioned JSON/XML conversion CLI, interactive JSON input, formatting verbs, and printed key-value-store errors.
- What you can do after
- Apply it via fmt functions to print, format strings, read simple input, and create or display formatted errors.
Learn Go with Pocket-Sized Projects
fmt is Go's standard library package for formatted I/O operations.
- How it is used
- Provides formatted output for Go programs, including simple debugging through Println.
- How deep it goes
- Explains importing fmt, calling Println, standard output, and exported names without detailing the wider formatting family.
- Examples
- Uses a main.go Hello world program and notes human-readable integer and Boolean output.
- What you can do after
- Apply it via fmt.Println to write strings and basic values to standard output.
Learn C++ by Example
fmt is an open-source C++ formatting library that provides format-string-based text formatting facilities.
- How it is used
- Provides portable formatted output when compiler support for std::format is incomplete.
- How deep it goes
- Explains installation, placeholders, specifiers, type checking, and alignment, but limits usage to commonly supported features.
- Examples
- Formats integers into a center-justified triangle using fixed and dynamically supplied widths.
- What you can do after
- Apply it via fmt::format to produce aligned, type-checked C++ output.
Related concepts
- fmt.Printlnhas part · fmt.Println is a Go standard-library function that writes its arguments separated by spaces and followed by a newline.
- import statementused by · An import statement is a source-code declaration that makes names or definitions from another module, package, or namespace available in the current scope.
- format methodalternative to · A format method is an API operation that produces a formatted representation by substituting supplied values into a formatting specification.
- standard librarykind of · A standard library is a collection of reusable modules, types, functions, APIs, and other facilities distributed with a programming language implementation or platform.
- packagekind of · A package is a programming-language namespace and organizational unit that groups related code and may define import, compilation, or access boundaries.
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