Because composite format strings are interpreted at runtime, rather than validated by the compiler, they can contain errors that lead to unexpected
behaviors or runtime errors. This rule statically validates the good behavior of composite formats when calling the methods of
String.Format
, StringBuilder.AppendFormat
, Console.Write
, Console.WriteLine
,
TextWriter.Write
, TextWriter.WriteLine
, Debug.WriteLine(String, Object[])
,
Trace.TraceError(String, Object[])
, Trace.TraceInformation(String, Object[])
,
Trace.TraceWarning(String, Object[])
and TraceSource.TraceInformation(String, Object[])
.
s = string.Format("{0}", arg0, arg1); // Noncompliant, arg1 is declared but not used. s = string.Format("{0} {2}", arg0, arg1, arg2); // Noncompliant, the format item with index 1 is missing so arg1 will not be used. s = string.Format("foo"); // Noncompliant, there is no need to use string.Format here.
s = string.Format("{0}", arg0); s = string.Format("{0} {1}", arg0, arg2); s = "foo";
const
. var pattern = "{0} {1} {2}"; var res = string.Format(pattern, 1, 2); // Compliant, not const string are not recognized
var array = new int[] {}; var res = string.Format("{0} {1}", array); // Compliant we don't know the size of the array
:
) is actually valid.