MISRA C:2012 Rule 3.1

The character sequences /* and // shall not be used within a comment

Description

Rule Definition

The character sequences /* and // shall not be used within a comment¹ .

Rationale

These character sequences are not allowed in code comments because:

• If your code contains a /* or a // in a /* */ comment, it typically means that you have inadvertently commented out code.

• If your code contains a /* in a // comment, it typically means that you have inadvertently uncommented a /* */ comment.

Polyspace Implementation

You cannot annotate this rule in the source code.

For information on annotations, see Annotate Code and Hide Known or Acceptable Results.

Additional Message in Report

The character sequence /* shall not appear within a comment.

Troubleshooting

If you expect a rule violation but do not see it, refer to Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

/* Used in // Comments

int x;
int y;
int z;

void non_compliant_comments ( void )
{
    x = y //  	/* Non-compliant
        + z
        //  */
        ;
    z++;	//	Compliant with exception: // permitted within a // comment
}

void compliant_comments ( void )
{
    x = y /*  	Compliant
      + z
	  */
        ;
    z++;	//	Compliant with exception: // is permitted within a // comment
}

In this example, in the non_compliant_comments function, the /* character occurs in what appears to be a // comment, violating the rule. Because of the comment structure, the operation that takes place is x = y + z;. However, without the two //-s, an entirely different operation x=y; takes place. It is not clear which operation is intended.

Use a comment format that makes your intention clear. For instance, in the compliant_comments function, it is clear that the operation x=y; is intended.

Check Information

Group: Comments

Category: Required

AGC Category: Required

Version History

Introduced in R2014b