A ( 65 ) - Z ( 90 ) a ( 97 ) - z ( 122 ) 0 ( 48 ) - 9 ( 57 ) enter - 13 space - 32 @ - 64 Who calls main()? OS. Execution starts at main. << : output / put to / stream insertion operator >> : input / get from / stream extraction operator calculation R to L printing L to R