Strings.Builder
strings.Builder is a Go standard-library type for efficiently accumulating text and producing the resulting string.
Go by Example
strings.Builder is a Go standard-library type that efficiently accumulates bytes or strings and converts the accumulated data to a string.
- How it is used
- Accumulates formatted URL text and captures CLI output for assertions through io.Writer.
- How deep it goes
- Explains Grow, write methods, zero-value use, pointer receivers, copying hazards, and String’s allocation-avoiding internal conversion.
- Examples
- Builds a URL String method and captures a CLI’s standard and error output with an in-memory builder.
- What you can do after
- Apply it to preallocate and assemble strings, or to record io.Writer output for tests.
Learn Go with Pocket-Sized Projects
strings.Builder is a Go standard-library type that efficiently accumulates string data while minimizing allocations.
- How it is used
- Builds a formatted feedback string efficiently while implementing the Stringer interface.
- How deep it goes
- Explains immutable strings, allocation costs, and a complete Builder loop, but stops short of detailed allocation internals.
- Examples
- Uses a word-game feedback type, hint status strings, a naive concatenation benchmark, and a Builder-based String method.
- What you can do after
- Apply it via Go's strings package to assemble repeated string output inside loops.
Read how Learn Go with Pocket-Sized Projects explains strings.Builder →
100 Go Mistakes and How to Avoid Them
strings.Builder is a Go type for efficiently accumulating string data and producing a final string.
- How it is used
- Optimizes concatenation of many strings by accumulating content in a reusable internal buffer.
- How deep it goes
- Explains immutability, internal byte-slice appends, interface-driven errors, Grow, and concurrency limits, then stops short of implementation source details.
- Examples
- Compares += concatenation with Builder, adds Grow based on summed byte lengths, and reports benchmark results for all three versions.
- What you can do after
- Build it from scratch using WriteString, Grow, and String while avoiding unnecessary allocation and unsynchronized sharing.
Read how 100 Go Mistakes and How to Avoid Them explains strings.Builder →
Related concepts
- concatenationalternative to · Concatenation is the operation of joining ordered sequences end to end to form a single sequence.
- io.Writerimplements · io.Writer is a Go interface whose Write method accepts a byte sequence and returns the number of bytes written and any error.
- slicinguses · Slicing selects or partitions a portion of an indexed sequence or multidimensional array, often along specified indices or dimensions.
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