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CS 170 – Intro to Scientific and engineering Programming

CS 170 – Intro to Scientific and engineering Programming . Data types. So far we have seen the following data types: Double Char String Other?. The class function. What is a class? A  class  is the blueprint from which individual objects are created . Ex. >> x = 14 x = 14

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CS 170 – Intro to Scientific and engineering Programming

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  1. CS 170 – Intro to Scientific and engineering Programming

  2. Data types • So far we have seen the following data types: • Double • Char • String • Other?

  3. The class function • What is a class? • A class is the blueprint from which individual objects are created. Ex.>> x = 14 x = 14 >> class(x) ans= double

  4. Numbers

  5. What’s the min? What’s the max? • >> intmax('int32') • ans = • 2147483647 • >> intmin('int32') • ans = • -2147483648 • >> realmax('single') • ans = • 3.4028e+038 • >> realmin('single') • ans = • 1.1755e-038

  6. Changing types • From int to double>> y = x y = 10 >> class(y) ans= Int8 • >> y = double(y) • y = • 10 • >> class(y) • ans = • double

  7. More changes >> int8(9.4) ans = 9 >> int8(-9.4) ans = -9 >> int8(-9.5) ans = -10 >> int8(128) ans = 127 >> int8(-1000) ans = -128

  8. Ascii characters

  9. Strings and functions • >> book_title = 'Matlab for Smarties‘ • >> length(book_title) • >> book_title(1) • >> book_title(4:16) • >> double(book_title) • >> s = 'Two is company, three a crowd.'; • >> ssub = s(13:end) • >> a = 'Three, two, one'; b = ', '; c = 'BLASTOFF!'; • >> count_down = [a,b,c]

  10. More string functions >> x = pi; >> fprintf('x:\nto three decimal places: %6.3f\n', x); x: to three decimal places: 3.142 >> s=sprintf('x:\nto three decimal places: %6.3f\n', x); >> s

  11. Even more… functions • char converts type to char • findstrfinds the positions of a substring in a string (see also strfind) • ischarreturns 1 if argument is a character array and 0 otherwise • isletterfinds letters in string • isspacefinds spaces, newlines, and tabs in string • isstrpropfinds characters of specified type in string • num2str converts number to string • length determines the number of characters in string • lower converts letters in string to lower case

  12. Even more… functions • regexpfinds substrings defined by a regular expression • sprintfwrites formatted data to string (cf. fprintf) • strcatconcatenates strings • strmatchsearch array for rows that begin with specified string • strncmpapplies strcmp to the first n characters of strings • strcmpreturns 1 if two strings are equal and 0 otherwise • strcmpilike strcmp but independent of case • strncmpcompares first n characters of strings • strncmpilike strncmp but independent of case • str2num converts string to number • upper converts string to upper case

  13. Questions??

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