CCMD (strlen)
{ if (argv.argc() == 2)
        Printf ("length: %d\n", SmallFont->StringWidth (argv[1]));
}

Quote

]strlen "blargh"
length: 48
]strlen "\cUblargh"
length: 48
]strlen "\c[Dark Gray]blargh"
length: 53

// the test console command needs to be different in ZDoom because the console doesn't auto-colorize strings there
CCMD (strlen)
{ if (argv.argc() == 2)
        Printf ("length: %d\n", SmallFont->StringWidth (strbin1 (argv[1])));
}