Writing and Reading a Binary File

Binary files are files that store data in binary format, such as images, videos, or compiled code.

#include <stdio.h>

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

int main() {
  struct Student s1 = {"Alice", 20, 3.75};
  struct Student s2;

  // Write the binary file
  FILE *filePtr = fopen("student.dat", "wb");
  if (filePtr == NULL) {
    printf("Error! Could not open file.\n");
    return 1;
  }
  fwrite(&s1, sizeof(struct Student), 1, filePtr);
  fclose(filePtr);

  // Read the binary file
  filePtr = fopen("student.dat", "rb");
  if (filePtr == NULL) {
    printf("Error! Could not open file.\n");
    return 1;
  }
  fread(&s2, sizeof(struct Student), 1, filePtr);
  fclose(filePtr);

  printf("Name: %s\nAge: %d\nGPA: %.2f\n", s2.name, s2.age, s2.gpa);

  return 0;
}

Explanation:

• fwrite(&s1, sizeof(struct Student), 1, filePtr): Writes the structure s1 to the binary file student.dat.
• fread(&s2, sizeof(struct Student), 1, filePtr): Reads the data from the binary file back into the structure s2.