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C OMP 401 B ASICS O F S CANNING Instructor: Prasun Dewan (FB 150, dewan@unc.edu)
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2 S CANNING P ROBLEM Scanning image for text. Scanning frequencies for radio stations. Finding words in a sentence Finding identifiers, operators, in a program
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3 S CANNING P ROBLEM Program name (First) Argument or option to the program output
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4 S CANNING JohnF.Kenndye token Input stream Input stream Token Stream Token Stream token
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5 A LGORITHM JohnF.Kenndye marker 0 Output: J
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6 A LGORITHM JohnF.Kenndye marker 1 Output: J String inputLine
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7 A LGORITHM JohnF.Kenndye marker 2 Output: J
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8 A LGORITHM JohnF.Kenndye marker 5 Output: JF
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9 A LGORITHM JohnF.Kenndye marker 6 Output: JF
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10 A LGORITHM JohnF.Kenndye marker 8 Output: JFK
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11 A LGORITHM JohnF.Kenndye marker 9 Output: JFK
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12 A LGORITHM JohnF.Kenndye marker 14 Output: JFK
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13 S OLUTION ( EDIT IN CLASS ) package warmup; public class AnUpperCasePrinter { public static void main(String[] args){ }
![13 S OLUTION ( EDIT IN CLASS ) package warmup; public class AnUpperCasePrinter { public static void main(String[] args){ }](http://images.slideplayer.com/25/7702342/slides/slide_14.jpg "13 S OLUTION ( EDIT IN CLASS ) package warmup; public class AnUpperCasePrinter { public static void main(String[] args){ }")
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14 S OLUTION public class AnUpperCasePrinter { public static void main(String[] args){ if (args.length != 1) { System.out.println("Illegal number of arguments:" + args.length + ". Terminating program."); System.exit(-1); } System.out.println("Upper Case Letters:"); int index = 0; while (index < args[0].length()) { if (Character.isUpperCase(args[0].charAt(index))) System.out.print(args[0].charAt(index)); index++; } System.out.println(); } Print on new vs previous line
![14 S OLUTION public class AnUpperCasePrinter { public static void main(String[] args){ if (args.length != 1) { System.out.println( Illegal number of arguments: + args.length + .](http://images.slideplayer.com/25/7702342/slides/slide_15.jpg "Terminating program. ); System.exit(-1); } System.out.println( Upper Case Letters: ); int index = 0; while (index < args[0].length()) { if (Character.isUpperCase(args[0].charAt(index))) System.out.print(args[0].charAt(index)); index++; } System.out.println(); } Print on new vs previous line.")
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15 D ETECTING U PPER C ASE public class AnUpperCasePrinter { public static void main(String[] args){ if (args.length != 1) { System.out.println("Illegal number of arguments:" + args.length + ". Terminating program."); System.exit(-1); } System.out.println("Upper Case Letters:"); int index = 0; while (index < args[0].length()) { char nextLetter = args[0].charAt(index) ; if (nextLetter >= ‘A’ && nextLetter <= ‘Z’ ) System.out.print(nextLetter); index++; } System.out.println(); } Successive uppercase letters/lowercase letters/digits are successive characters in Java’s ordered character sequence
![15 D ETECTING U PPER C ASE public class AnUpperCasePrinter { public static void main(String[] args){ if (args.length != 1) { System.out.println( Illegal number of arguments: + args.length + .](http://images.slideplayer.com/25/7702342/slides/slide_16.jpg "Terminating program. ); System.exit(-1); } System.out.println( Upper Case Letters: ); int index = 0; while (index < args[0].length()) { char nextLetter = args[0].charAt(index) ; if (nextLetter >= ‘A’ && nextLetter <= ‘Z’ ) System.out.print(nextLetter); index++; } System.out.println(); } Successive uppercase letters/lowercase letters/digits are successive characters in Java’s ordered character sequence.")
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16 D EMO Scanning Algorithm Demo
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