C++ - Structure
- Structure ये एक अलग-अलग data types का collection होता है |
- अगर structure का इस्तेमाल करना हो तो 'struct' keyword का इस्तेमाल करते है |
- Structure ये array के जैसा ही होता है |
- Array similar data types का collection होता है और Structure different data type का collection होता है |
- Structure में किये हुए हर variable के decaration को 'member' कहते है |
- Structure हर एक member के लिए अलग-अलग memory allocate करता है |
Syntax for Structure Definition
struct structure_name{
data_type member 1;
data_type member 2;
------------------
------------------
data_type memeber n;
};
Example for Structure Definition
struct Employee{
int emp_id;
char emp_name[30];
float salary;
};
यहाँ पर example में structure का नाम 'Employee' लिया है और structure के तीन Members है जिनके अलग-अलग तीन data types है | एक 'emp_id' के लिए integer है, एक 'emp_name' के लिए character है, एक float है जो 'salary' के लिए है |
Structure Variable Declaration
Structure का variable declare करने के दो प्रकार है |- जब Structure की definition लिखी जाती तब वहा पर भी Structure variable को लिखा जाता है |
- Structure के variable को main() function के अंदर भी किया जाता है |
Syntax for Structure Variable outside of Structure Definition
struct structure_name{
data_type member 1;
data_type member 2;
------------------
------------------
data_type memeber n;
}structure_variable(s);
Example for Structure Variable in main() Function
struct Employee{
int emp_id;
char emp_name[30];
float salary;
}info;
Syntax for Structure Variable in main() Function
struct structure_name{
data_type member 1;
data_type member 2;
------------------
------------------
data_type memeber n;
}structure_variable(s);
int main(){
struct structure_name structure_variable_name;
}
Example for Structure Variable in main() Function
struct Employee{
int emp_id;
char emp_name[30];
float salary;
};
int main(){
struct Employee info;
}
Structure के Members या Elements को access कैसे किया जाता है ?
Syntax for Accesing Structure members
structure_variable_name . member_of_structure = value(optional);Example for Accesing Structure members
info.emp_id = 10;
Structure Initilization
Structure Initialization के दो प्रकार है |
Type 1 :
struct Employee{
int emp_id;
char emp_name[30];
float salary;
};
int main(){
struct Employee info;
info.emp_id = 34;
strcpy( info.emp_name, "Raj Biradar");
info.salary = 20000.00;
}
Type 2 :
struct Employee{
int emp_id;
char emp_name[30];
float salary;
};
int main(){
struct Employee info = {34, "Raj Biradar", 20000.00};
}
Full Example for Structure
Source Code :
#include <iostream.h>
#include <string.h>
using namespace std;
struct Employee {
int emp_id;
char emp_name[30];
float salary;
}info;
int main(){
info.emp_id = 34;
strcpy( info.emp_name, "Raj Biradar");
info.salary = 20000.50;
cout<<"Employee id is : "<<info.emp_id<<endl;
cout<<"Employee name is : "<<info.emp_name<<endl;
cout<<"Employee salary is : "<<info.salary<<endl;
return 0;
}
Output :
Employee id is : 34 Employee name is Raj Biradar Employee salary is : 20000.5
Structure working with size(sizeof)
Structure के member अलग-अलग memory allocate करता है और पूरा Structure का size उनके members के जितनी होती है |
Source Code :
#include <iostream.h>
#include <string.h>
using namespace std;
struct Employee {
int emp_id;
char emp_name[20];
float salary;
};
int main(){
struct Employee info;
cout<<"Size of Employee id is : "<<sizeof(info.emp_id)<<" bytes."<<endl; // size of emp_id
cout<<"Size of Employee name : "<<sizeof(info.emp_name)<<" bytes."<<endl; // size of emp_name
cout<<"Size of Employee salary is : "<<sizeof(info.salary)<<" bytes."<<endl; // size of salary
cout<<"Size of Employee structure : "<<sizeof(info)<<" bytes."<<endl; // size of Employee
return 0;
}
Ouutput :
Size of Employee id is : 4 bytes Size of Employee name : 20 bytes Size of Employee salary is : 4 bytes Size of Employee structure : 28 bytes
Structure Memory Representation
Memory Representation में देखे तो System 32-bit होने के कारण integer का size '4 Bytes' होता है | character का size bracket में दिए हुए size जितना ही होता है और float का size 4 Bytes ही होता है | Structure का size दिए हुए सभी Members के size जितना होता है | for eg. 4 (int) + 20 (char) + 4 (float) = 28 Bytes होता है |
Structure using Pointer
Structure के Members को दो प्रकार से access किया जाता है |- . (dot Operator)
- -> (pointer Operator)
Accessing Members using pointer Operator
Source Code :
#include <iostream.h>
#include <string.h>
using namespace std;
struct Employee {
int emp_id;
char emp_name[30];
float salary;
};
int main(){
struct Employee info;
struct Employee *ptr;
ptr = &info;
ptr->emp_id = 34;
strcpy( ptr->emp_name, "Raj Biradar");
ptr->salary = 20000.00;
cout<<"Employee id is : "<<ptr->emp_id<<endl;
cout<<"Employee name is : "<<ptr->emp_name<<endl;
cout<<"Employee salary is : "<<ptr->salary<<endl;
return 0;
}
< /pre>
Output :
Employee id is : 34 Employee name is Raj Biradar Employee salary is : 20000.000000
Array of Structure
Syntax for Array Structure Declaration
struct structure_name structure_variable_name[array_size];
Example for Array Structure Declaration
struct Employee info[3];
अगर एक से ज्यादा Employee की information store करनी हो तो array का इस्तेमाल करता है |
Example for Structure Without using Array
Source Code :
#include <iostream.h>
#include <string.h>
using namespace std;
struct Employee{
int emp_id;
char emp_name[20];
float salary;
};
int main(){
struct Employee info1, info2, info3;
info1.emp_id=34;
strcpy(info1.emp_name, "Raj");
info1.salary = 20000.00;
info2.emp_id=35;
strcpy(info2.emp_name, "Maruti");
info2.salary = 30000.00;
info3.emp_id=36;
strcpy(info3.emp_name, "Suraj");
info3.salary = 40000.00;
cout<<"Student 1"<<endl;
cout<<"Employee id is : "<<info1.emp_id<<endl;
cout<<"Employee name is : "<<info1.emp_name<<endl;
cout<<"Employee salary is : "<<info1.salary<<endl<<endl;
cout<<"Student 2"<<endl;
cout<<"Employee id is : "<<info2.emp_id<<endl;
cout<<"Employee name is : "<<info2.emp_name<<endl;
cout<<"Employee salary is : "<<info2.salary<<endl<<endl;
cout<<"Student 3"<<endl;
cout<<"Employee id is : "<<info3.emp_id<<endl;
cout<<"Employee name is : "<<info3.emp_name<<endl;
cout<<"Employee salary is : "<<info3.salary<<endl;
return 0;
}
Output :
Student 1 Employee id is : 34 Employee name is Raj Employee salary is : 20000.000000 Student 2 Employee id is : 35 Employee name is Maruti Employee salary is : 30000.000000 Student 3 Employee id is : 36 Employee name is Suraj Employee salary is : 40000.000000
Same Example for Structure using Array
#include <iostream.h>
#include <string.h>
using namespace std;
struct Employee{
int emp_id;
char emp_name[20];
float salary;
};
int main(){
struct Employee info[3];
int i;
info[0].emp_id=34;
strcpy(info[0].emp_name, "Raj");
info[0].salary = 20000.00;
info[1].emp_id=35;
strcpy(info[1].emp_name, "Maruti");
info[1].salary = 30000.00;
info[2].emp_id=36;
strcpy(info[2].emp_name, "Suraj");
info[2].salary = 40000.00;
for(i=0; i<3; i++){
cout<<"Student "<<i+1<<endl;
cout<<"Employee id is : "<<info[i].emp_id<<endl;
cout<<"Employee name is : "<<info[i].emp_name<<endl;
cout<<"Employee salary is : "<<info[i].salary<<endl<<endl;
}
return 0;
}
Output :
Student 1 Employee id is : 34 Employee name is Raj Employee salary is : 20000.000000 Student 2 Employee id is : 35 Employee name is Maruti Employee salary is : 30000.000000 Student 3 Employee id is : 36 Employee name is Suraj Employee salary is : 40000.000000