Defining and Accessing Structs in C Language

In C language, a struct is a user-defined data type that allows the combination of different types of data into a single entity. By using structs, related data can be managed conveniently, making the program clearer and easier to maintain. This article will detail how to define structs and access their members, suitable for beginners.

1. What is a Struct

In C language, a struct is a data structure that allows us to group different types of variables together. In practical applications, if you want to handle data with common characteristics, you can use a struct to represent it. These data are referred to as “members”.

For example, a struct representing student information might include name, age, and score.

2. Defining a Struct

To define a struct, we use the struct keyword, and the basic syntax is as follows:

struct StructureName {    DataType member1;    DataType member2;    // More members can be added};

Example: Defining a Struct for Student Information

Below is a sample code that demonstrates how to create a struct named Student, which contains three members: name, age, and score.

#include <stdio.h>
// Define the Student struct
struct Student {    char name[100];  // Name    int age;        // Age    float score;    // Score};

Here, we first include the header file <stdio.h>, and then we create the Student type using struct, which contains three different data fields.

3. Creating and Initializing a Struct Variable

Once we have defined a new data type, we can declare a variable of that type and initialize it. For example:

#include <stdio.h>
#include <string.h>
int main() {    struct Student student1;  // Declare student1 as Student type
    // Initialize field values    strcpy(student1.name, "Alice");   // Input name, need to include string library <string.h>
    student1.age = 20;                  // Input age
    student1.score = 88.5f;             // Input score
    printf("Student Name: %s\n", student1.name);
    printf("Student Age: %d\n", student1.age);
    printf("Student Score: %.2f\n", student1.score);
    return 0;}

Notes:

In the above example, since we need to copy string content into the name field, we need to include the header file <string.h>.
Use the dot operator (.) to reference a field.

4. Accessing Multiple Instances

Multiple entities of the same type can be declared, and their values can be assigned and output separately. The following code demonstrates this process:

#include <stdio.h>
#include <string.h>
int main() {    struct Student students[2];      // Array to store two Students
    strcpy(students[0].name, "Alice");     students[0].age = 20;     students[0].score = 88.5f;
    strcpy(students[1].name, "Bob");     students[1].age = 21;     students[1].score = 92.3f;
    for(int i=0; i<2; i++) {          printf("Student Name: %s\n", students[i].name);          printf("Student Age: %d\n", students[i].age);          printf("Student Score: %.2f\n\n", students[i].score);      }
    return 0;}

In this example, we use an array to store multiple Student instances and then loop through to output the information of each instance.

5. Conclusion

Through the above content, we have learned how to define and use various user-defined data types in C programming language—namely, “data encapsulation”. Mastering this concept will make programming easier and more logical. Additionally, many advanced concepts such as pointers and dynamic memory allocation can be combined with what you have learned to enhance your programming skills, enabling you to tackle more complex software development projects in the future!

I hope this article helps you gain a deeper understanding of how to effectively organize and manage related information in C language design. If you have any further questions, please feel free to ask.