PD Lec2 PDF
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University of Khartoum
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Summary
This document is a lecture on data structures in C++, covering fields, records, files, arrays, stacks, and queues. It includes examples and explains the concepts. The lecture was delivered by a university department of electrical and electronic engineering.
Full Transcript
Lecture (2) Fields, Records, Files Arrays Stacks Queues 2 Data structure means the way by which we structurally organize the data in memory to determine the efficiency with which different operations on the information are carried ou...
Lecture (2) Fields, Records, Files Arrays Stacks Queues 2 Data structure means the way by which we structurally organize the data in memory to determine the efficiency with which different operations on the information are carried out. We must choose the data structures carefully on the basis of which operation the application will use most frequently. 3 A field is an item of stored data, and could be a name, an address, a date, a description, a quantity etc. A field is defined with given a name (identifier) and a type. The data type defines the data that will be stored in the field. 4 Examples of fields: String firstName; int quantity; Boolean isInteger; A record is a collection of fields that related to a single entity. A student record may include student id, name, birth date, address and GPA fields. 5 General syntax in C++: sruct StructName; { data type identifier; … } Struct is a collection of fields of a different data types. The fields of struct are referred to as members. The individual member of struct be accessed by the name of the struct followed by the name of the member. thePerson.firstName = “Ahmed”; cout > employee.empName; cin >> employee.empPayRec.salary; 8 A file is a collection of related records. For example, a student file might include all of the records of students enrolled at school and a police department might keep a file of criminal records. Files are stored on a secondary storage devices such as disks, cloud, etc. 9 Key is a field in a data file containing information capable of uniquely identifying a record in relation to all other records in the same data file. No two records within a file can have the same key value. Data records stored on files can be accessed and processed later. The file can be of a fixed length record or a variable length record. 10 An array is a fixed number of elements of the same type stored sequentially in memory. An integer array holds some number of integers and a character array holds some number of characters and so on. The size of array is referred to as its dimension. To declare an array in C++: type arrayName [ dimension ] 11 To declare an integer array named arr of four elements: int arr To initialize its elements, we use: arr = 15; arr = 21; arr = 9; arr = 13; OR arr = { 15, 21, 9,13 } Sometimes it is convenient to let the compiler determine the size of the array: int arr { 9, 0, 6, 7, 12, 10, 14 } When accessing an array the index given must be a positive integer from 0 to n-1, where n is the dimension of the array. 12 #include using namespace std; int main() { int arr; cout arr[i]; // inputting array values } cout
