Saturday, 8 February 2014

C – Structure using Pointer

Prev Next

C structure can be accessed in 2 ways in a C program. They are,

Using normal structure variable
Using pointer variable

Dot(.) operator is used to access the data using normal structure variable and arrow (->) is used to access the data using pointer variable. You have learnt how to access structure data using normal variable in C – Structure topic. So, we are showing here how to access structure data using pointer variable in below C program.

Example program for C structure using pointer:

In this program, “record1″ is normal structure variable and “ptr” is pointer structure variable. As you know, Dot(.) operator is used to access the data using normal structure variable and arrow(->) is used to access data using pointer variable.

#include <stdio.h>
#include <string.h>

struct student 
{
     int id;
     char name[30];
     float percentage;
};

int main() 
{
     int i;
     struct student record1 = {1, "Raju", 90.5};
     struct student *ptr;

     ptr = &record1;     

         printf("Records of STUDENT1: \n");
         printf("  Id is: %d \n", ptr->id);
         printf("  Name is: %s \n", ptr->name);
         printf("  Percentage is: %f \n\n", ptr->percentage);

     return 0;
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[30];

float percentage;

};

int main()

{

int i;

struct student record1 = {1, "Raju", 90.5};

struct student *ptr;

ptr = &record1;

printf("Records of STUDENT1: \n");

printf(" Id is: %d \n", ptr->id);

printf(" Name is: %s \n", ptr->name);

printf(" Percentage is: %f \n\n", ptr->percentage);

return 0;

}

Output:

Records of STUDENT1:
Id is: 1
Name is: Raju
Percentage is: 90.500000

Example program to copy a structure in C:

There are many methods to copy one structure to another structure in C.

We can copy using direct assignment of one structure to another structure or
we can use C inbuilt function “memcpy()” or
we can copy by individual structure members.

#include <stdio.h>
#include <string.h>

struct student 
{
    int id;
    char name[30];
    float percentage;
};

int main() 
{
    int i;
    struct student record1 = {1, "Raju", 90.5};
    struct student record2, *record3, *ptr1, record4;

    printf("Records of STUDENT1 - record1 structure \n");
    printf("  Id : %d \n  Name : %s\n  Percentage : %f\n",
            record1.id, record1.name, record1.percentage);

    // 1st method to copy whole structure to another structure
    record2=record1;    

    printf("\nRecords of STUDENT1 - Direct copy from " \
           "record1 \n");
    printf("  Id : %d \n  Name : %s\n  Percentage : %f\n", 
            record2.id, record2.name, record2.percentage);

    // 2nd method to copy using memcpy function
    ptr1 = &record1; 
    memcpy(record3, ptr1, sizeof(record1));

    printf("\nRecords of STUDENT1 - copied from record1 " \
           "using memcpy \n");
    printf("  Id : %d \n  Name : %s\n  Percentage : %f\n", 
           record3->id, record3->name, record3->percentage);

    // 3rd method to copy by individual members
    printf("\nRecords of STUDENT1 - Copied individual " \
           "members from record1 \n");
    record4.id=record1.id;
    strcpy(record4.name, record1.name);
    record4.percentage = record1.percentage;

    printf("  Id : %d \n  Name : %s\n  Percentage : %f\n", 
            record4.id, record4.name, record4.percentage);

     return 0;
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[30];

float percentage;

};

int main()

{

int i;

struct student record1 = {1, "Raju", 90.5};

struct student record2, *record3, *ptr1, record4;

printf("Records of STUDENT1 - record1 structure \n");

printf(" Id : %d \n Name : %s\n Percentage : %f\n",

record1.id, record1.name, record1.percentage);

// 1st method to copy whole structure to another structure

record2=record1;

printf("\nRecords of STUDENT1 - Direct copy from " \

"record1 \n");

printf(" Id : %d \n Name : %s\n Percentage : %f\n",

record2.id, record2.name, record2.percentage);

// 2nd method to copy using memcpy function

ptr1 = &record1;

memcpy(record3, ptr1, sizeof(record1));

printf("\nRecords of STUDENT1 - copied from record1 " \

"using memcpy \n");

printf(" Id : %d \n Name : %s\n Percentage : %f\n",

record3->id, record3->name, record3->percentage);

// 3rd method to copy by individual members

printf("\nRecords of STUDENT1 - Copied individual " \

"members from record1 \n");

record4.id=record1.id;

strcpy(record4.name, record1.name);

record4.percentage = record1.percentage;

printf(" Id : %d \n Name : %s\n Percentage : %f\n",

record4.id, record4.name, record4.percentage);

return 0;

}

Output:

Records of STUDENT1 - record1 structure
Id : 1
Name : Raju
Percentage : 90.500000 Records of STUDENT1 – Direct copy from record1
Id : 1
Name : Raju
Percentage : 90.500000
Records of STUDENT1 – copied from record1 using memcpy
Id : 1
Name : Raju
Percentage : 90.500000
Records of STUDENT1 – Copied individual members from record1
Id : 1
Name : Raju
Percentage : 90.500000

Passing struct to function in c

Passing struct to function

Prev Next

A structure can be passed to any function from main function or from any sub function.
Structure definition will be available within the function only.
It won’t be available to other functions unless it is passed to those functions by value or by address(reference).
Else, we have to declare structure variable as global variable. That means, structure variable should be declared outside the main function. So, this structure will be visible to all the functions in a C program.

Passing structure to function in C:

It can be done in below 3 ways.

Passing structure to a function by value
Passing structure to a function by address(reference)
No need to pass a structure – Declare structure variable as global

Example program – passing structure to function in C by value:

In this program, the whole structure is passed to another function by value. It means the whole structure is passed to another function with all members and their values. So, this structure can be accessed from called function. This concept is very useful while writing very big programs in C.

#include <stdio.h>
#include <string.h>

struct student 
{
            int id;
            char name[20];
            float percentage;
};

void func(struct student record);

int main() 
{
            struct student record;

            record.id=1;
            strcpy(record.name, "Raju");
            record.percentage = 86.5;

            func(record);
            return 0;
}

void func(struct student record)
{
            printf(" Id is: %d \n", record.id);
            printf(" Name is: %s \n", record.name);
            printf(" Percentage is: %f \n", record.percentage);
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[20];

float percentage;

};

void func(struct student record);

int main()

{

struct student record;

record.id=1;

strcpy(record.name, "Raju");

record.percentage = 86.5;

func(record);

return 0;

}

void func(struct student record)

{

printf(" Id is: %d \n", record.id);

printf(" Name is: %s \n", record.name);

printf(" Percentage is: %f \n", record.percentage);

}

Output:

Id is: 1

Name is: Raju

Percentage is: 86.500000

Example program – Passing structure to function in C by address:

In this program, the whole structure is passed to another function by address. It means only the address of the structure is passed to another function. The whole structure is not passed to another function with all members and their values. So, this structure can be accessed from called function by its address.

#include <stdio.h>
#include <string.h>

struct student 
{
           int id;
           char name[20];
           float percentage;
};

void func(struct student *record);

int main() 
{
          struct student record;

          record.id=1;
          strcpy(record.name, "Raju");
          record.percentage = 86.5;

          func(&record);
          return 0;
}

void func(struct student *record)
{
          printf(" Id is: %d \n", record->id);
          printf(" Name is: %s \n", record->name);
          printf(" Percentage is: %f \n", record->percentage);
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[20];

float percentage;

};

void func(struct student *record);

int main()

{

struct student record;

record.id=1;

strcpy(record.name, "Raju");

record.percentage = 86.5;

func(&record);

return 0;

}

void func(struct student *record)

{

printf(" Id is: %d \n", record->id);

printf(" Name is: %s \n", record->name);

printf(" Percentage is: %f \n", record->percentage);

}

Output:

Id is: 1

Name is: Raju

Percentage is: 86.500000

Example program to declare a structure variable as global in C:

Structure variables also can be declared as global variables as we declare other variables in C. So, When a structure variable is declared as global, then it is visible to all the functions in a program. In this scenario, we don’t need to pass the structure to any function separately.

#include <stdio.h>
#include <string.h>

struct student 
{
            int id;
            char name[20];
            float percentage;
};
struct student record; // Global declaration of structure

void structure_demo();

int main() 
{
            record.id=1;
            strcpy(record.name, "Raju");
            record.percentage = 86.5;

            structure_demo();
            return 0;
}

void structure_demo()
{
            printf(" Id is: %d \n", record.id);
            printf(" Name is: %s \n", record.name);
            printf(" Percentage is: %f \n", record.percentage);
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[20];

float percentage;

};

struct student record; // Global declaration of structure

void structure_demo();

int main()

{

record.id=1;

strcpy(record.name, "Raju");

record.percentage = 86.5;

structure_demo();

return 0;

}

void structure_demo()

{

printf(" Id is: %d \n", record.id);

printf(" Name is: %s \n", record.name);

printf(" Percentage is: %f \n", record.percentage);

}

Output:

Id is: 1

Name is: Raju

Percentage is: 86.500000

……

Prev Next

Array of Structures in c

C – Array of Structures

Prev Next

As you know, C Structure is collection of different datatypes ( variables ) which are grouped together. Whereas, array of structures is nothing but collection of structures. This is also called as structure array in C.

……

Example program for array of structures in C:

This program is used to store and access “id, name and percentage” for 3 students. Structure array is used in this program to store and display records for many students. You can store “n” number of students record by declaring structure variable as ‘struct student record[n]“, where n can be 1000 or 5000 etc.

#include <stdio.h>
#include <string.h>

struct student 
{
     int id;
     char name[30];
     float percentage;
};

int main() 
{
     int i;
     struct student record[2];

     // 1st student's record
     record[0].id=1;
     strcpy(record[0].name, "Raju");
     record[0].percentage = 86.5;

     // 2nd student's record         
     record[1].id=2;
     strcpy(record[1].name, "Surendren");
     record[1].percentage = 90.5;

     // 3rd student's record
     record[2].id=3;
     strcpy(record[2].name, "Thiyagu");
     record[2].percentage = 81.5;

     for(i=0; i<3; i++)
     {
         printf("     Records of STUDENT : %d \n", i+1);
         printf(" Id is: %d \n", record[i].id);
         printf(" Name is: %s \n", record[i].name);
         printf(" Percentage is: %f\n\n",record[i].percentage);
     }
     return 0;
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[30];

float percentage;

};

int main()

{

int i;

struct student record[2];

// 1st student's record

record[0].id=1;

strcpy(record[0].name, "Raju");

record[0].percentage = 86.5;

// 2nd student's record

record[1].id=2;

strcpy(record[1].name, "Surendren");

record[1].percentage = 90.5;

// 3rd student's record

record[2].id=3;

strcpy(record[2].name, "Thiyagu");

record[2].percentage = 81.5;

for(i=0; i<3; i++)

{

printf(" Records of STUDENT : %d \n", i+1);

printf(" Id is: %d \n", record[i].id);

printf(" Name is: %s \n", record[i].name);

printf(" Percentage is: %f\n\n",record[i].percentage);

}

return 0;

}

Output:

Records of STUDENT : 1
Id is: 1
Name is: Raju
Percentage is: 86.500000

Records of STUDENT : 2
Id is: 2
Name is: Surendren
Percentage is: 90.500000

Records of STUDENT : 3
Id is: 3
Name is: Thiyagu
Percentage is: 81.500000

Example program for declaring many structure variable in C:

In this program, two structure variables “record1″ and “record2″ are declared for same structure and different values are assigned for both structure variables. Separate memory is allocated for both structure variables to store the data.

#include <stdio.h>
#include <string.h>

struct student 
{
     int id;
     char name[30];
     float percentage;
};

int main() 
{
     int i;
     struct student record1 = {1, "Raju", 90.5};
     struct student record2 = {2, "Mani", 93.5};

     printf("Records of STUDENT1: \n");
     printf("  Id is: %d \n", record1.id);
     printf("  Name is: %s \n", record1.name);
     printf("  Percentage is: %f \n\n", record1.percentage);

     printf("Records of STUDENT2: \n");
     printf("  Id is: %d \n", record2.id);
     printf("  Name is: %s \n", record2.name);
     printf("  Percentage is: %f \n\n", record2.percentage);

     return 0;
}

#include <stdio.h>

#include <string.h>

struct student

{

int id;

char name[30];

float percentage;

};

int main()

{

int i;

struct student record1 = {1, "Raju", 90.5};

struct student record2 = {2, "Mani", 93.5};

printf("Records of STUDENT1: \n");

printf(" Id is: %d \n", record1.id);

printf(" Name is: %s \n", record1.name);

printf(" Percentage is: %f \n\n", record1.percentage);

printf("Records of STUDENT2: \n");

printf(" Id is: %d \n", record2.id);

printf(" Name is: %s \n", record2.name);

printf(" Percentage is: %f \n\n", record2.percentage);

return 0;

}

Output:

Records of STUDENT1:
Id is: 1
Name is: Raju
Percentage is: 90.500000
Records of STUDENT2:
Id is: 2
Name is: Mani
Percentage is: 93.500000

TUTORIALS POINT

Pages

Saturday, 8 February 2014

C – Structure using Pointer

C – Structure using Pointer

Prev Next

Example program for C structure using pointer:

Output:

Example program to copy a structure in C:

Output:

Passing struct to function in c

Passing struct to function

Prev Next

Passing structure to function in C:

Example program – passing structure to function in C by value:

Output:

Example program – Passing structure to function in C by address:

Output:

Example program to declare a structure variable as global in C:

Output:

Prev Next

Array of Structures in c

C – Array of Structures

Prev Next

Example program for array of structures in C:

Output:

Example program for declaring many structure variable in C:

Output:

Prev Next