V3025. Incorrect format. Consider checking the N format items of the 'Foo' function.

The analyzer has detected a possible error related to use of formatting methods: String.Format, Console.WriteLine, Console.Write, etc. The format string does not correspond with actual arguments passed to the method.

Here are some simple examples:

Unused arguments.

int A = 10, B = 20;
double C = 30.0;
Console.WriteLine("{0} < {1}", A, B, C);

Format item {2} is not specified, so variable 'C' won't be used.

Possible correct versions of the code:

//Remove extra argument
Console.WriteLine("{0} < {1}", A, B);

//Fix format string
Console.WriteLine("{0} < {1} < {2}", A, B, C);

Number of arguments passed is less than expected.

int A = 10, B = 20;
double C = 30.0;
Console.WriteLine("{0} < {1} < {2}", A, B);
Console.WriteLine("{1} < {2}", A, B);

A much more dangerous situation occurs when a function receives fewer arguments than expected. This will raise a FormatException exception.

Possible correct versions of the code:

//Add missing argument
Console.WriteLine("{0} < {1} < {2}", A, B, C);

//Fix indices in format string
Console.WriteLine("{0} < {1}", A, B);

The analyzer doesn't output the warning given that:

• The number of format items specified matches the number of arguments.
• The format object is used a number of times:

int row = 10;
Console.WriteLine("Line: {0}; Index: {0}", row);

Here is an example of this bug in a real-life application:

var sql = string.Format(
  "SELECT {0} FROM (SELECT ROW_NUMBER() " +
  " OVER (ORDER BY {2}) AS Row, {0} FROM {3} {4}) AS Paged ",
  columns, pageSize, orderBy, TableName, where);

The function receives 5 formatting objects, but the 'pageSize' variable is not used as format item {1} is missing.

This diagnostic is classified as:

Was this page helpful?

Message submitted.

Your message has been sent. We will email you at

If you do not see the email in your inbox, please check if it is filtered to one of the following folders:

• Promotion
• Updates
• Spam

If you can’t find an answer to your question, fill in the form below and our developers will contact you

By clicking this button you agree to our Privacy Policy statement