Correct spacing between roman numbers in toc for parts

Question

In my document, the roman numbers to the left of the part names are too close to the text.

I use this snippet the following codesnippet to correct the issue, but it gives me an undefined control sequence.

\ifthenelse{\boolean{@parts}} {\renewcommand{\thepart}{\hspace{-0.5em}\hbox to 1em{\hfill\roman{part}}}}{}

The error:

Undefined control sequence ...0.5em}\hbox to 1em{\hfill\roman{part}}}}{}
Extra \fi ...0.5em}\hbox to 1em{\hfill\roman{part}}}}{}

Another thing is that the roman numbers are not in lowercase. Is it possible to make them uppercase instead?

Image of the problem:

Thanks.

Answer 1

I don't know how you made the ToC to crash the numbers into the titles (a complete MWE would be great), but controlling the appearance of the ToC is best left to package tocloft. There it is recommended to use

\setlength{\cftpartnumwidth}{3cm}

to set the width reserved for the number of the part.