Consider the following code snippet:
int executionTimes = 1000;
DateTime finishTime = DateTime.Now;
string msg = "Execution details: " + executionTimes.ToString("#,000.00") + " times; finished " + finishTime.ToString("dd/MM/yyyy hh:mm");
When invoking the "Use string.Format" suggestion, it yields:
string.Format("Execution details: {0} times; finished {1}", executionTimes.ToString("#,000.00"), finishTime.ToString("dd/MM/yyyy hh:mm"))
When, in fact, I'd expect it to yield:
string.Format("Execution details: {0:#,000.00} times; finished {1:dd/MM/yyyy hh:mm}", executionTimes, finishTime)