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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.
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#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.
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#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 |
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