Chapter 11 Structured Data

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Chapter 11 Structured Data
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Arrays are ADTs all components or "members"
must be the same data type example int ids5
each element is an int C allows you to group
several variables together even though they are
different data types into one data
structure struct students int
grades5 double gpa struct
stu_rec long socsecnum char
lastname10 char firstname10 students
pupil No storage has been allocated yet. The
structures have only been defined.
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Declare an array of structures stu_rec
class24135 // an array of 35 stu_rec
structures stu_rec temp // one struct of
stu_rec stu_rec a, b, c // 3 structs of
stu_rec
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struct stu_rec struct students long
socsecnum int grades5 char
lastname10 double gpa char
firstname10 students pupil stu_rec
student student.socsecnum 123456789 strcpy(st
udent.lastname, "Jones" ) strcpy(student.firstnam
e, "Indiana" ) student.pupil.grades0
100 student.pupil.grades1 99 student.pupil.g
pa 99.5 cin gtgt student.pupil.grades2 cout
ltlt student.pupil.gpa cout ltlt student.lastname
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// Anonymous structure prohibit using the
structure after the initial declarations have
been made include ltiostreamgt using namespace
std struct // notice! No tagname char
Name25 int grades5 student, sptr
student int main( ) cout ltlt "Enter the
students name " cin.get(student.Name,
25) cin.ignore(100, '\n') for( int i 0 i
lt 5 i) // I controls the loop, sptr the
grades cout ltlt endl ltlt "Enter grade " ltlt i
1 cin gtgt sptr-gtgradesi return 0
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When to use . When to use -gt When to use
struct GradeInfo char Name25 int
TestScores float Average GradeInfo
StPtr, Student StPtr Student Equivalent
Statements StPtr-gtTestScores (StPtr).TestScore
s // compare addresses StPtr-gtTestScores
(StPtr).TestScores // compare values
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When to use . When to use -gt When to use
struct GradeInfo char Name25 int
TestScores float Average GradeInfo
Student1 int scores 82, 93, 74
Student1.TestScores scores // TestScores
ptr has been init cout ltlt Student1.TestScores
// print the pointer GradeInfo StPtr cout ltlt
StPtr-gtTestScores // points to
scores Sptr-gtTestscores //
incrementTestScores pointer, not data!
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struct Student // Arrays of Structures char
Name25 int grades5 int main( )
Student student35, sptr student // declare
an array of 35 stu structs for(int j
0 j lt 35 j, sptr) cout ltlt "Enter
the students name " cin.get(studentj.Name,
25) cin.ignore(100, '\n') for( int i 0 i
lt 5 i) cout ltlt endl ltlt "Enter grade " ltlt
i 1 cin gtgt sptr-gtgradesi // end
grades // end student return 0
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Anonymous Unions

• The members of an anonymous union have names, but
  the union itself has no name.
• union union
• member declarations long yard
• . . . short feet

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// Demonstrates how members can be overwritten in
a union include ltiostreamgt using namespace
std int main( ) union long lvar short
svar lvar 1000000 svar 111 //
first 2 bytes of lvar about to be
overwritten cout ltlt lvar ltlt endl cout ltlt
svar ltlt endl return 0 Output 65647 111
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UNIONS OF STRUCTURES struct MANAGER struct
LABORER EMPNAME emane EMPNAME
ename int dept int dept float
salary float hourlywage float
hoursworked union EMPLOYEE MANAGER
mgr LABORER laborer EMPLOYEE emp //
declare one var of type EMPLOYEE cin.get(emp.labor
er.ename.lname, 20) cin gtgt emp.laborer.dept cout
ltlt emp.laborer.hoursworked
emp.laborer.hourlywage cin gtgt emp.mgr.salary //
oops! Overwrite laborer info