Currently, sprintf str, "%;",  throws the following exception: ';' is not a valid sprintf format. It would be more clear if it displayed the entire format there, including the %.
sprintf str, "%;", 
';' is not a valid sprintf format
First thought on implementation: keep an index for the % character and then substr between there and the current position before throwing the exception.
I've started a new branch, whiteknight/sprintf_cleanup, to work on several issues related to the sprintf code, including this ticket. I will post updates as the work progresses.
Attempt to fix error messages a little bit, on request from benabik++…
… (GH #759)
A few small code cleanups. Fix t/op/sprintf.t, since it is wonderfull…
…y matching on the exact text of the exception message, which is changing for GH #759
@benabik The error message has been updated to say:
"'%c' is not valid in sprintf format sequence '%Ss'"
Where the second parameter is the text of the format sequence so far. Once the state machine finds one incorrect character it can't keep going to find the complete intended format, so this is the best we can do. If this is acceptable to you, I'll merge my branch to master and close this ticket.
I have just merged this branch to master. The error message is improved as best as I can make it. I'm closing this ticket.