问题:

I am using Delphi 5 and Fast Report 4 to make a report application. I have defined a variable "ReportTitle" in MyReport.f3 at design time and I assigned a value for it at runtime. Why is my code raising an EStackOverflow Exception?

Here is the code sample

  frxrprt1.LoadFromFile('c:\MyReport.fr3');
  frxrprt1.Variables['ReportTitle'] := 'Sales Summary Report';
  frxrprt1.ShowReport;

回答1:

Use this:

frxrprt1.Variables['ReportTitle'] := '''Sales Summary Report''';

The "variable" values are actually treated as full-fledged expressions; If you want it to be a string, it needs to be a standard pascal constant, using single-tick quoting; And since you're doing that from pascal code, you need to quote the quotes by double-quoting.

You probably get the stack overflow because fast report's scripting engine is trying to make sense of whatever you wrote and runs into a recursive problem.

回答2:

Or you can use another way.

  frxrprt1.Variables['ReportTitle'] := QuotedStr('Sales Summary Report');

The function QuotedStr returns the string S, quoted with single quotes. This means that S is enclosed in single quotes, and every single quote in S is doubled. It is equivalent to a call to AnsiQuotedStr(s, '''').