Return statement

As explained in Modern C

A return statement is a C control-flow statement that ends execution of the current function and optionally supplies a return value.

A return statement ends execution of the current function and transfers control to the statement that called it. In main, `return EXIT_SUCCESS;` sends an `int` value back to the platform startup routine. When printf returns, execution resumes in main where the call stopped. section 2.4.3

Returning from a function

A function with a non-void return type must provide an expression at each return point. For example: bool leapyear(unsigned year) { return !(year % 4) && ((year % 100) || !(year % 400)); } The returned expression is converted to the function's declared return type when necessary. A function declared `void` may use `return;` without an expression. section 7.1

Key rules:

• A function has one entry point but can contain several return statements. section 7.1
• Match every return with the function declaration: value-returning functions require expressions, while void functions must omit them. section 7.1
• Reaching the closing brace is equivalent to `return;` only for a void function; value-returning functions must not simply reach the end. section 7.1

Figure 2.1. Execution of a small program

Trace the calls from platform startup to main and printf, then follow each return to the point where execution resumes. section 2.4.3

How Modern C covers it

How deep it goes

Defines control transfer, typed expressions, multiple returns, and closing-brace behavior, but defers implementation internals.

Examples

Uses main returning EXIT_SUCCESS, printf returning to main, and leapyear returning a Boolean expression.

What it assumes

Assumes declared functions and basic types while establishing function calls and returns through concrete C examples.

What you can do after

Apply it via C syntax to return control and correctly typed values from functions.

How it connects

Connects function calls, function declarations, control flow, types, and the void type.

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Related concepts

• yieldcontrasts with · A language construct that yields control from a computation, optionally passing a value to another context, and may allow the suspended computation to continue later.
• return valueconfigures · A return value is the result produced by a function, method, or operation and supplied to the code that invoked it.
• Noneproduces · None is Python’s singleton object representing the absence of a value or meaningful result.
• functionused by · A function is a defined operation that maps inputs to outputs and, when implemented as a callable program unit, may also produce effects.
• throwcontrasts with · A throw construct explicitly raises or propagates an exception, error, or value to transfer control nonlocally from normal execution.

This explainer was generated by Manning's knowledge graph from the text of Modern C. The section links point to the parts of the book it draws on.