Chapter 27 Putting it all together. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page1

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Lucinda Shields
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2 Requirements The program must be long enough to demonstrate modular programming Short enough the fit into a chapter Complex enough to demonstrate advanced C++ features Simple enough for a student to understand It must be useful. The program selected is designed to read C++ files and generate simple statistics. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page2

3 (0 {0 #include /*********************************************** char int ***********************************************/ calcresult; oper_char; value; --<iostream> a simple // // value the // 4operator function result specified ofthe calculator the after user calc. the specified op. * Specification Preliminary Specification for a C++ Statistics Gathering Program Steve Oualline February 10, 1995 The program stat gathers statistics about C++ source files and prints them. The command line is: stat <files..> Where <files..> is a list of source files. The following shows the output of the program on a short test file. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page3

4 Total Maximum Number Comment (0 (0 {0 {1 number {2 {1 {0 of nesting toint { blank comment lines } code ofmain() result // while } return only lines: with ratio loop only }() {} lines (1) code = (0); : % forever 47 lines 0; 24 {...35 and...4 comments (or // until initialize break reached) the result Specification... Practical C++ Programming Copyright 2003 O'Reilly and Associates Page4

5 Code Design Token Module Turns input into tokens (a series of words ) Example: answer = ( ) / 89; // Compute something becomes: T_ID The word "answer" T_OPERATOR The character "=" T_L_PAREN Left Parenthesis T_NUMBER The number 123 T_OPERATOR The character "+" T_NUMBER The number 456 T_R_PAREN The right parenthesis T_OPERATOR The Divide operator T_NUMBER The number 89 T_OPERATOR The semicolon T_COMMENT The // comment T_NEW_LINE The end of line character Practical C++ Programming Copyright 2003 O'Reilly and Associates Page5

6 Other Modules Character type module Determines the type of a character (letter, digit, etc.) Statistics class Consumes tokens and outputs statistics. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page6

7 Functional Description char_type class. Basically a big table indexed by character type. Some extra code thrown in for specials like C_ALPHA_NUMRIC. input_file An ifstream with line buffering that copies each line to the output. token class Reads characters, outputs tokens. There is one trick in the coding, the use of the TOKEN_LIST macro. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page7

8 TOKEN_LIST #define TOKEN_LIST \ T(T_NUMBER), /* Simple number (float or int) */ \ T(T_STRING), /* String or character constant */ \ T(T_COMMENT), /* Comment */ \ T(T_NEWLINE), /* Newline character */ \ T(T_OPERATOR), /* Arithmetic operator */ \ T(T_L_PAREN), /* Character "(" */ \ T(T_R_PAREN), /* Character ")" */ \ T(T_L_CURLY), /* Character "{" */ \ T(T_R_CURLY), /* Character "}" */ \ T(T_ID), /* Identifier */ \ T(T_EOF) /* End of File */ Practical C++ Programming Copyright 2003 O'Reilly and Associates Page8

9 class virtualstat void{ take_token(token_type line_start(void) eof(void) {}; {}; token) = 0; Functional description (cont ) stat class public: }; line_counter class Counts the number of T_NEW_LINE tokens. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page9

10 void switch if max_level case // Consume (cur_level Ignore brace_counter::take_token(token_type T_L_CURLY: T_R_CURLY: (token) = tokens, cur_level; > { max_level) count the nesting of {} token) { brace_counter class ++cur_level; break; --cur_level; break; default: } } break; Practical C++ Programming Copyright 2003 O'Reilly and Associates Page10

11 // void std::cout max_level Output namely brace_counter::line_start(void) brace_counter::eof(void) eof the << '{' "Maximum '\n'; current statistics total of<< number cur_level nesting statistics number of lines { of << {}' '; :{" << brace_counter class (cont.) std::cout.setf(ios::left); std::cout.width(2); } std::cout.unsetf(ios::left); std::cout.width(); } Practical C++ Programming Copyright 2003 O'Reilly and Associates Page11

12 Functional Description paren_counter class Almost the same as brace counter. comment_counter class Keeps track of lines with comments, lines of code, lines with both comment and code and blank lines. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page12

13 // static A list line_counter paren_counter brace_counter comment_counter stat of*stat_list[] the statistics line_count; paren_count; brace_count; comment_count; = { we collecting // Counter of lines () {} cmt levels info do_file procedure Reads tokens and stuffs them into the statistics classes. Uses the statistics list for stuffing: }; &line_count, &paren_count, &brace_count, &comment_count, NULL Practical C++ Programming Copyright 2003 O'Reilly and Associates Page13

14 * const static char // This T_L_PAREN, T_L_CURLY T_R_CURLY T_EOF *name int is T_COMMENT, voida LINE_MAX = mult-line do_file( "Test" T_R_PAREN T_NEWLINE = 500; const comment char // T_STRING // *const T_ID, name) T_OPERATOR, T_NUMBER * Test file /******************************************************** ********************************************************/ { } Practical C++ Programming Copyright 2003 O'Reilly and Associates Page14

Chapter - 8 More Control Statements. Practical C++ Programming Copyright 2003 O'Reilly and Associates Page 1

Chapter - 8 More Control Statements Practical C++ Programming Copyright 2003 O'Reilly and Associates Page 1 for Statement General form: for (initial-statement; condition; iteration-statement) body-statement;