Gerard,

Alex pointed you to ways of handling Macro Substitution, but from your example it doesn't seem like you really need it. Would just using the variables not work?

System.Diagnostics.Process.Start("MailMergeApp.exe", var1 + " " + var2 + " " + var3);

You also may want to look into the ProcessInfo class. It gives you more options for starting processes.

HTH,
Chad

>How is Macro Substitution done in cSharp
>
>I want to run an external exe with parameters and the syntax that works fine is:
>
>System.Diagnostics.Process.Start("MailMergeApp.exe","aaaa bbbb cccccc");
>
>However, I really want to use aaaaa, bbbbb and cccc as variables, so in VFP terms, I want to macro substitute with the values in aaaa bbbb and cccc
>
>(I have three strings with thee values already defined)
>
>Regards,
>
>Gerard