411 REFERENCE · Wikibooks
C++ Language/Type/Literals/FinancialThousandMarkers
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
A number like one million cannot be programmed as 1,000,000 because the comma is used for other purposes.
But you can write a numeric literal as 1'000'000.
Additional information about 1000-markers (includes interactive examples)