How to define and use pointers to structures in the C language.

1 year ago
Olivia Parker
2 minutes

Below are the definition and usage methods of C language structure pointers.

  1. Define a structure type: First, it is necessary to define a structure type that can contain multiple fields (member variables).

For example, define a struct type that represents student information.

struct Student {
    char name[50];
    int age;
    float score;
};
  1. Declare a pointer variable of a struct: Use the defined struct type to declare a struct pointer variable.

For example, declaring a pointer variable pointing to a student structure:

struct Student *ptr;
  1. Dynamically allocate memory: Assign memory space for a struct pointer variable.

For example, dynamically allocate memory using the malloc function.

ptr = (struct Student*)malloc(sizeof(struct Student));
  1. Using a struct pointer: accessing and modifying the fields of a struct using pointer variables.

For example, accessing and modifying fields in a student structure.

strcpy(ptr->name, "Tom");
ptr->age = 18;
ptr->score = 89.5;
  1. Freeing memory: After using a structure pointer, memory space needs to be released.

For example, releasing memory using the free function:

free(ptr);

The complete example code is as follows:

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

struct Student {
    char name[50];
    int age;
    float score;
};

int main() {
    struct Student *ptr;
    ptr = (struct Student*)malloc(sizeof(struct Student));
    if (ptr == NULL) {
        printf("Memory allocation failed.\n");
        return -1;
    }
    strcpy(ptr->name, "Tom");
    ptr->age = 18;
    ptr->score = 89.5;
    
    printf("Name: %s\n", ptr->name);
    printf("Age: %d\n", ptr->age);
    printf("Score: %.2f\n", ptr->score);
    
    free(ptr);
    
    return 0;
}

Output:

Name: Tom
Age: 18
Score: 89.50
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