CERT C: Rec. DCL20-C

Explicitly specify void when a function accepts no arguments

Since R2026a

Description

Explicitly specify void when a function accepts no arguments¹

Polyspace Implementation

The rule checker checks for Use of function declarators with empty parentheses.

Examples

Use of function declarators with empty parentheses

Issue

The rule checker reports a violation if a function declaration uses empty parenthesis () instead of (void) to indicate no parameters.

Risk

If a function is declared with an empty parameter list, the compiler does not check if the function is called with a parameter at all. At compile time, the compiler can accept a call to the function with arbitrary parameters. Such a function declaration is ambiguous and can result in issues such as undefined behavior and buffer overflow.

Fix

If a function accepts no arguments, then explicitly declare a void parameter in the function parameter list. Use the void parameter for both declaration and definition of a function.

Example

In this header file, the function myFunction() is declared using empty parentheses to indicate that the function accepts no argument. Polyspace^® reports a violation.

// my_function.h
#ifndef MY_FUNCTION_H
#define MY_FUNCTION_H

void myFunction(); //Noncompliant

#endif // MY_FUNCTION_H

Correction

To fix this violation, use void in the argument list to indicate that the function myFunction accepts no arguments.

// my_function.h
#ifndef MY_FUNCTION_H
#define MY_FUNCTION_H

void myFunction(void); //Compliant

#endif // MY_FUNCTION_H

Check Information

Group: Rec. 02. Declarations and Initialization (DCL)

PQL Name: std.cert.DCL20_C

Version History

Introduced in R2026a