C++ L07-Struct

Mohammad Shaker
mohammadshaker.com
@ZGTRShaker
2010, 11, 12, 13, 14
C++
Programming Language
L07 -STRUCTS

Float, double, long double
C++ data types
Structured
Simple
Address
Pointer
Reference
enum
Floating
Array
Struct
Union
Class
Char, Short, int, long, bool
Integral

Structs
•Differentiate:
–Array:
•Is a collection of variables of the same type
–Struct“Structure”
•Is a collection of variable of one or more type
•Structis definition not a declaration
–No memory allocation
•“Memory is allocated just when we declare a variable”
–Examples:
•Student record, banks, players, addresses

Structs
#include<iostream>
usingnamespace::std;
voidmain(void)
{
structMyInner
{
intKey;
intSalary;
};
structEmployee
{
MyInner info;
charName[20];
};
}
#include<iostream>
voidmain(void)
{
inti = 0;
structEmployee
{
inta, b, c;
} TempStruct [2] = {{2,4,5}, {1,6,8}};
cout << TempStruct[i].a << endl;
cout << TempStruct[i].b << endl;
cout << TempStruct[i].c << endl;
}
2
4
5
Press any key to continue

Structs
#include<iostream>
voidmain(void)
{
inti = 0;
structEmployee
{
inta, b, c;
} TempStruct [2] = {{2,4}, {1,6,8}};
}
2
4
0
#include<iostream>
voidmain(void)
{
inti = 1;
structEmployee
{
inta, b, c;
} TempStruct [2] = {{2,4} };
}
0
0
0

Structs
#include<iostream>
voidmain(void)
{
inti = 1;
structEmployee
{
inta, b, c;
};
Employee TempStruct [2] = {{2,4} };
}
0
0
0
#include<iostream>
voidmain(void)
{
inti = 1;
structEmployee
{
inta, b, c;
} TempStruct [2] = {{2,4} }
}
Compiler error.
Missing semi colon be4 cout “;” (After TempStruct)

Structs
#include<iostream>
voidmain(void)
{
inti = 1;
structEmployee
{
inta, b, c;
} TempStruct [2] = {{2,4} }
}
Compiler error.
Missing semi colon be4 cout “;” (After TempStruct)
#include<iostream>
voidmain(void)
{
inti = 0;
struct
{
inta, b, c;
} TempStruct [2] = {{2,8} };
}
2
8
0

Structs
#include<iostream>
voidmain(void)
{
inti = -1;
struct
{
inta, b, c;
} TempStruct [2] = {{2,8} };
TempStruct[i].c = 67;
}
Compiler error. When not writing the name of the struct we should declare variable immediately
#include<iostream>
voidmain(void)
{
inti = -1;
struct
{
inta, b, c;
} TempStruct [2] = {{2,8} };
}
2030155668
1
1698745032

Structs
#include<iostream>
voidmain(void)
{
inti = 0;
struct
{
inta, b, c;
};
TempStruct [2] = {{2,8} };
}
1231378292
1
1689373384
#include<iostream>
voidmain(void)
{
inti = 1;
struct
{
inta, b, c;
} TempStruct [2] = {{2,8} };
}
0
0
67

Structs
#include<iostream>
voidmain(void)
{
inti = 1;
struct
{
inta, b, c;
} TempStruct [2] = {{2,8} };
TempStruct.c = 67;
}
Compiler error
#include<iostream>
voidmain(void)
{
inti = 1;
struct
{
inta, b, c;
} TempStruct [2] = {{2,8} };
cout << TempStruct << endl;
}
001BF048

Structs
#include<iostream>
voidmain(void)
{
structstudent
{
charName[20];
intNum;
intid;
};
student st1 = {"mee", 196, 7};
}
Compile and run
#include<iostream>
voidmain(void)
{
structstudent
{
charName[20];
intNum;
intid;
};
st1 = {"zee", 111, 4};
}
Compiler error

Structs
#include<iostream>
voidmain(void)
{
structstudent
{
charName[20];
intNum;
intid;
};
student st2 = {"zee", 111, 4};
student Tempst1 = {"mee", 196, 7};
if(st1.Num == Tempst1.Num)
{
cout << "Yeah!"<< endl;
}
else
{
cout << "No!"<< endl;
}
}
Yeah!
because Structs are “value” type unlike classes which are “reference”type
#include<iostream>
voidmain(void)
{
structstudent
{
charName[20];
intNum;
intid;
};
if (st1 == Tempst1)
{
}
else
{
}
}
Compiler error

Structs
#include<iostream>
voidmain(void)
{
structstudent
{
charName[20];
intNum;
intid;
};
if(st1.Num = st2.Num)
{
}
else
{
}
cout << st1.Num << endl;
cout << st2.Num << endl;
}
Yeah!
111
111

Structs
#include<iostream>
voidmain(void)
{structInner
{
intNum;
intid;
};
structstudent
{
charName[20];
Inner info;
};
student st1 = {"mee", { 11, 3 } };
student &Tempst1 = st1;
cout << st1. Name << endl;
cout << st1.info. Num++ << endl;
cout << st1.info.id << endl;
cout << ++Tempst1.info. Num << endl;
}
mee
11
3
13
#include<iostream>
voidmain(void)
{structInner
{
intNum;
intid;
};
structstudent
{
charName[20];
Inner info;
};
student st1 = {"mee", { 11, 3 } };
cout << st1. Num++ << endl;
cout << st1.info.id << endl;
cout << ++Tempst1.info.Num << endl;
}
Compiler error

Structs
#include<iostream>
voidmain(void)
{
structInner
{
intNum;
intid;
};
structstudent
{
charName[20];
Inner info;
};
student st1 = {"mee", 11, 3 };
cout << st2.info. Num++ << endl;
cout << st2. info. id << endl;
cout << ++Tempst1. info. Num << endl;
}
mee
111
4
12
#include<iostream>
voidmain(void)
{
structInner
{
intNum;
intid;
};
structstudent
{
string Name;
Inner info;
};
st1.Name = "foo";
cout << st1.Name << endl;
}
Compiler error

Structs
#include<iostream>
#include<string>
voidmain(void)
{
structInner
{
intNum;
intid;
};
structstudent
{
string Name;
Inner info;
};
st1.Name = "foo";
}
foo
#include<iostream>
#include<string>
voidmain(void)
{
structInner
{
intNum;
intid;
};
structstudent
{
string Name;
Inner info;
};
st1.Name = "foo";
cout << st1 << endl;
}
Compiler error

Structs
#include<iostream>
#include<string>
structInner{intNum;intid;};
structstudent{string Name;Inner info;};
student Print(student stu)
{
cout << stu.Name << endl;
returnstu;
}
voidmain(void)
{
Print(st1);
}
mee
#include<iostream>
#include<string>
{
returnstu;
}
voidmain(void)
{
structInner
{intNum;intid;};
structstudent
{string Name;Inner info;};
Print(st1);
}
Compiler error
Inner student are in main and not global to let the function see them!

Structs
#include<iostream>
#include<string>
structInner
{
intNum;
intid;
};
structstudent
{
string Name;
Inner info;
};
{
stu.Name = "GoGo";
returnstu;
}
voidmain(void)
{student st1 = {"mee", 11, 3 };
Print(st1);
}
mee
mee
#include<iostream>
#include<string>
structInner
{
intNum;
intid;
};
structstudent
{
string Name;
Inner info;
};
student Print(student &stu)
{
stu.Name = "GoGo";
returnstu;
}
voidmain(void)
{student st1 = {"mee", 11, 3 };
Print(st1);
}
mee
GoGo

Structs
#include<iostream>
#include<string>
structInner
{intNum;intid;};
structstudent
{string Name;Inner info; };
student Go()
{
student stu;
stu.Name = "GoGo";
returnstu;
}
voidmain(void)
{student st1 = {"mee", 11, 3 };
st1=st2;
st1=Go();
}
zee
GoGo

Pointers and Structs
#include<iostream>
#include<string>
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
student *ptr = &st1;
cout << ptr << endl;
}
Compile and run
#include<iostream>
#include<string>
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << *ptr << endl;
}
Compiler error
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << ptr->Name << endl;
cout << ptr->info.id << endl;
}
0025F27C
mee
7
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << ptr->info->id << endl;
}
Compiler error, -> before info

structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << *(ptr->Name) << endl;
cout << *(ptr->info.id) << endl;
}
Compiler error
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << (*ptr).Name << endl;
cout << (*ptr).info.id << endl;
}
mee
7
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << (*ptr)->Name << endl;
cout << (*ptr)->info.id << endl;
}
Compiler error

#include<iostream>
#include<string>
structInner
{intNum; intArr[3];};
structstudent
voidCount(student stu)
{
inttotal = 0;
for(inti = 0; i<3; i++)
{
total += stu.info.Arr[i];
}
cout << total << endl;
stu.info.Arr[0]=3;
}
voidmain(void)
{
student st1 = {"mee", 196, 1,3,3};
Count(st1);
Count(st1);
}
7
7
#include<iostream>
#include<string>
structInner
structstudent
voidCount(student *stu)
{
inttotal = 0;
for(inti = 0; i<3; i++)
{
total += stu->info.Arr[i];
}
stu->info.Arr[0]=3;
}
voidmain(void)
{
student st = {"mee", 196, 1,3,3};
student *st1 = &st;
Count(st1);
Count(st1);
}
7
9

#include<iostream>
#include<string>
structInner
structstudent
voidCount(student *&stu)
{
inttotal = 0;
for(inti = 0; i<3; i++)
{
total += stu->info.Arr[i];
}
stu->info.Arr[0]=3;
}
voidmain(void)
{
student st = {"mee", 196, 1,3,3};
student *st1 = &st;
Count(st1);
Count(st1);
}
7
9
#include<iostream>
#include<string>
structInner
structstudent
voidCount(student &stu)
{
inttotal = 0;
for(inti = 0; i<3; i++)
{
total += stu.info.Arr[i];
}
stu.info.Arr[0]=3;
}
voidmain(void)
{
student st1 = {"mee", 196, 1,3,3};
Count(st1);
Count(st1);
}
7
9

StructsMembers and Functions
#include<iostream>
#include<string>
structstudent
{
string Name;
voidprint()
{
cout << Name << endl;
}
};
voidmain(void)
{
student st1 = {"mee"};
st1.print();
}
mee
#include<iostream>
#include<string>
structstudent
{
string Name;
voidprint()
{
cout << student.Name << endl;
}
};
voidmain(void)
{
st1.print();
}
Compiler error
Function print is implicitely inline

#include<iostream>
#include<string>
structstudent
{
string Name;
voidprint()
{
}
voidChangeName(string str)
{
Name = str;
}
};
voidmain(void)
{
string NewName= "zee";
st1.print();
st1.ChangeName(NewName);
st1.print();
}
mee
zee

#include<iostream>
#include<string>
structstudent
{
string Name;
voidstudent::print();
voidChangeName(string str);
};
voidstudent::print()
{
}
voidstudent::ChangeName(string str)
{
Name = str+Name;
}
voidmain(void)
{
st1.print();
st1.ChangeName(“foo”);
st1.print();
}
mee
foomee
Now the functions are not implicitely inline
#include<iostream>
#include<string>
structstudent
{
string Name;
voidstudent::print();
};
{
}
{
Name = str;
}
voidmain(void)
{
st1.print();
st1.ChangeName(“foo”);
st1.print();
}
mee
foo
Now the functions are not implicitely inline

•privatedata members
–Private access
•Can be used by a few categories of functions
•publicdata members
–Public access
•Can be used by all code

#include<iostream>
#include<string>
structstudent
{
private:
intTempID;
public:
intID;
string Name;
voidChangeID(intn);
voidprint();
};
{cout << Name << endl; }
{Name = str+Name;}
voidstudent::ChangeID(intn)
{TempID = 2;
ID = n+TempID;
cout << "Your ID = "<< ID << endl;}
voidmain(void)
{intn = 3; string NewName= "zee";
student st1;st1.print();
st1.ChangeName(NewName);st1.print(); TempID=5;
st1.ChangeID(n);
}
Compiler error
Un delcared identifier
#include<iostream>
#include<string>
structstudent
{
private:
intTempID;
public:
intID;
string Name;
voidChangeID(intn);
voidprint();
};
{Name = str+Name;}
{TempID = 2;
ID = n+TempID;
voidmain(void)
st1.ChangeName(NewName);st1.print();
st1.ChangeID(n);
}
zee
Your ID = 5

#include<iostream>
#include<string>
structstudent
{
private:
intTempID;
public:
intID;
string Name;
voidChangeID(intn);
voidprint();
};
{Name = str+Name;}
{TempID = 2;
ID = n+TempID;
voidmain(void)
st1.ChangeName(NewName);st1.print(); st1.TempID=5; st1.ChangeID(n);}
Compiler error
Can’t access private data memebers

Quiz 1, 2, 3, 4
#include <iostream>
using namespace::std;
void main(void)
{
inti= 1;
structMyFirstS
{
inta, b, c;
} TempStruct[2] = {{2,4} }
cout<< TempStruct[i].a << endl;
cout<< TempStruct[i].b << endl;
cout<< TempStruct[i].c << endl;
}
Compiler error Missing;
#include <iostream>
void main(void)
{
inti= 0;
struct
{
inta, b, c;
};
TempStruct[2] = {2,8,10};
cout<< TempStruct[i].a << endl;
cout<< TempStruct[i].b << endl;
cout<< TempStruct[i].c << endl;
}
Compiler error, TempStructhas no type!
#include <iostream>
void main(void)
{
string NewName= “wa3wa3"
structstudent
{
char Name[20];
intNum;
intid;
};
st1 = {NewName, 111, 4};
}
Compiler error
structInner
{intNum;intid;};
structstudent
voidmain(void)
{
cout << ptr->info->id << endl;
}
Compiler error, -> before info

Quiz 5, 6
#include <iostream>
#include <string>
structInner
structstudent
void Count(student &stu)
{
inttotal = 0;
for (int i = 0; i<3; i++)
{
total += 2*stu.info.Arr[i];
}
cout<< total << endl;
stu.info.Arr[1]=-3;
}
void main(void)
{
student st1 = {"mee", 196, 1,3,3};
Count(st1);
Count(st1);
}
14
2
#include <iostream>
#include <string>
structstudent
{public:
intID; string Name;
void ChangeID(intn);
void print();
void ChangeName(string str);
};
void student::print()
{cout<< Name << endl; }
void student::ChangeName(string str)
{Name = str+Name;}
void student::ChangeID(intn)
{
static intTempID= 4;
TempID+= 2;
ID = n+TempID;
cout<< "Your ID = " << ID << endl;}
void main(void)
{int n = 3; string NewName= "zee";
st1.ChangeID(n);
n = 5;
st1.ChangeID(n);}
zee
Your ID = 9
zeezee
Your ID = 13

C++ L07-Struct

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