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CHAPTER 21 File Handling This section shows File Handling in Pascal: Pascal treats a file as a sequence of components, which must be of uniform type. A file's type is determined by the type of the components. File data type is defined as: type file-name = file of base-type; Where, the base-type indicates the type of the components of the file. The base type could be anything like, integer, real, Boolean, enumerated, subrange, record, arrays and sets except another file type. Variables of a file type are created using the var declaration: var f1, f2,...: file-name; Following are some examples of defining some file types and file variables: type rfile = file of real; ifile = file of integer; bfile = file of boolean; datafile = file of record arrfile = file of array[1..4] of integer; var marks: arrfile; studentdata: datafile; rainfalldata: rfile; tempdata: ifile; choices: bfile; TUTORIALS POINT Simply Easy Learning Page 114
Creating and Writing to a File Let us write a program that would create a data file for students' records. It would create a file named students.dat and write a student's data into it: program DataFiles; type StudentRecord = Record s_name: String; s_addr: String; s_batchcode: String; end; var Student: StudentRecord; f: file of StudentRecord; begin Assign(f,'students.dat'); Rewrite(f); Student.s_name := 'John Smith'; Student.s_addr := 'United States of America'; Student.s_batchcode := 'Computer Science'; Write(f,Student); Close(f); end. When compiled and run, the program would create a file named students.dat into the working directory. You can open the file using a text editor, like notepad, to look at John Smith's data. Reading from a File We have just created and written into a file named students.dat. Now, let us write a program that would read the student's data from the file: program DataFiles; type StudentRecord = Record s_name: String; s_addr: String; s_batchcode: String; end; var Student: StudentRecord; f: file of StudentRecord; begin assign(f, 'students.dat'); reset(f); while not eof(f) do begin read(f,Student); writeln('Name: ',Student.s_name); writeln('Address: ',Student.s_addr); writeln('Batch Code: ', Student.s_batchcode); end; close(f); end. TUTORIALS POINT Simply Easy Learning Page 115
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Pascal Tutorial
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ABOUT THE TUTORIAL Pascal Tutorial
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Declaring Constants ...............
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Accessing Two-Dimensional Array Ele
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CHAPTER 1 Pascal Overview This chap
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CHAPTER 2 Environment This section
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Name and version of text editor can
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Pascal Hello World Example Followin
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CHAPTER 4 Basic Syntax You have see
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The Pascal character set consists o
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Type Declarations: The type declara
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Subrange Types Subrange types allow
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Pascal programming language also al
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Enumerated Variables You have seen
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CHAPTER 7 Constants This section sh
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CHAPTER 8 Operators This section sh
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Checks if the value of left operand
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When the above code is compiled and
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program beBitwise; var a, b, c: int
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CHAPTER 9 Decision Making This sect
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Example: Let us try a complete exam
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Example: Let us try a complete exam
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Nested if-then Statements It is alw
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The following rules apply to a case
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Flow Diagram: Example: The followin
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CHAPTER 10 Loops This section shows
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Flow Diagram: Here, key point of th
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Flow Diagram Example: program forLo
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Example: program repeatUntilLoop; v
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Example: program exBreak; var a: in
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Example: program exContinue; var a:
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Example: The following program illu
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Defining a Function: In Pascal, a f
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Page 71 and 72: variable named m. The variable m is
Page 73 and 74: program exRecursion; var num, f: in
Page 75 and 76: procedure swap(x, y: integer); var
Page 77 and 78: When the above code is compiled and
Page 79 and 80: Now, let us extend the program litt
Page 81 and 82: Let us change the previous example
Page 85 and 86: 12 function AnsiStrLower( Str: PCha
Page 87 and 88: CHAPTER 15 Boolean This section sho
Page 89 and 90: CHAPTER 16 Arrays This section show
Page 91 and 92: Initializing Arrays In Pascal, arra
Page 93 and 94: Two-Dimensional Arrays: The simples
Page 95 and 96: The following example declares and
Page 97 and 98: Passing Arrays as Subprogram Argume
Page 99 and 100: Following are some valid pointer de
Page 101 and 102: To check for a nil pointer, you can
Page 103 and 104: program exPointers; const MAX = 3;
Page 105 and 106: program exPointers; const MAX = 3;
Page 107 and 108: Value of num = 3000 Value available
Page 109 and 110: CHAPTER 18 Records This section sho
Page 111 and 112: (* book 2 specification *) Book2.ti
Page 113 and 114: type record-ptr = ^ record-name; re
Page 115 and 116: (* book 1 specification *) Book1.ti
Page 117 and 118: Example: The following example woul
Page 119: Set Operators You can perform the f
Page 128 and 129: Reads data from a file into memory
Page 130 and 131: Reads from file into variable and g
Page 132 and 133: CHAPTER 22 Memory Management This s
Page 134 and 135: Resizing and Releasing Memory When
Page 136 and 137: Frees dynamically allocated memory
Page 138 and 139: Returns segment 37 procedure SetMem
Page 140 and 141: eadkey; clrscr; gotoxy(20,3); write
Page 144 and 145: Program DateDemo; uses sysutils; va
Page 146 and 147: 14 function EncodeDate( Year: Word;
Page 148 and 149: 39 function TimeStampToDateTime( co
Page 150 and 151: Objects This section shows the conc
Page 152 and 153: type Rectangle = object private len
Page 156 and 157: egin r1.init(3, 7); writeln('Draw a
Page 158 and 159: function TableTop.getmaterial(): st
Page 160 and 161: Classes This section shows the clas
Page 162 and 163: {$mode objfpc} // directive to be u
Page 164 and 165: Constructors and Destructors for Pa
Page 166 and 167: program inheritanceExample; {$MODE
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