Label
A label is a named code location or construct that control-flow operations can reference as a target.
Modern C, Third Edition
A label is an identifier followed by a colon that marks a statement as a target for a goto statement.
- How it is used
- Uses labels with goto for exceptional local cleanup and selected algorithmic control-flow changes.
- How deep it goes
- Explains syntax, same-function transfer, lifetime effects, and safety constraints, but stops short of long jumps and concurrency.
- Examples
- Uses RETRY, NEW_LINE, ASCEND, and a compound-literal example to contrast loop and goto repetition.
- What you can do after
- Apply it via goto for constrained cleanup or algorithmic transfers while checking object scope and lifetime.
Classic Game Programming on the NES: Make your own retro video game
A label is a symbolic identifier assigned to a code location so assembly instructions can refer to that location without specifying its numeric address.
- How it is used
- Names jump, branch, and call destinations while also making fixed NES system values readable.
- How deep it goes
- Defines label syntax and scopes, explains assembler address resolution, and notes branch-range errors without detailing machine-code encoding.
- Examples
- Demonstrates `NEWCODE`, a `ClearMemory` procedure with `@Loop`, unnamed loop labels, and named PPU, APU, and controller values.
- What you can do after
- Apply it via an assembler to write readable control-flow targets and scoped loop labels without manually calculating addresses.
Read how Classic Game Programming on the NES: Make your own retro video game explains label →
Modern C
A label is a named position in assembler code that identifies a point to which control can refer or transfer.
- How it is used
- Marks destinations for exceptional control-flow changes and for identifying positions in generated assembler.
- How deep it goes
- Explains C and assembler roles, then connects repeated execution to scope and lifetime without developing label syntax broadly.
- Examples
- Uses RETRY and AGAIN labels, goto repetition, compound literals, and fgoto assembler output.
- What you can do after
- Evaluate how C labels redirect execution and how corresponding assembler labels identify machine-level program positions.
Related concepts
- gotoused by · A goto statement or instruction unconditionally transfers program execution to a labeled statement or location within the current execution unit.
- 6502 assemblerused by · A program that translates 6502 assembly-language source code into machine code.
- break statementconfigures · A break statement terminates the nearest supported enclosing loop, switch, or similar control construct and transfers control to the following statement.
- continue statementuses · A continue statement skips the remainder of the current loop iteration and proceeds to the loop’s next control step.
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