C语言数据结构和读写文件

base/fread.c

@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// 保持结构体定义与写入时完全一致
+struct Book {
+    char title[50];
+    char author[50];
+    float price;
+};
+
+struct FileHeader {
+    char magic[4];    // 魔数 "BOOK"
+    int version;      // 版本号
+    int count;        // 书籍总数
+};
+
+int main() {
+    FILE *fp = fopen("books.dat", "rb"); // "rb" 表示二进制读取模式
+
+    // 1. 先读取文件头
+    struct FileHeader header;
+    if (fread(&header, sizeof(struct FileHeader), 1, fp) != 1) {
+        printf("读取文件头失败！\n");
+        fclose(fp);
+        return 1;
+    }
+
+    // 3. 根据文件头里的 count 动态分配内存
+    struct Book *books = (struct Book *)malloc(header.count * sizeof(struct Book));
+    if (books == NULL) {
+        printf("内存分配失败！\n");
+        fclose(fp);
+        return 1;
+    }
+
+    // 4. 一次性读取所有书籍数据
+    // 从当前文件指针位置（文件头之后）开始读
+    size_t read_count = fread(books, sizeof(struct Book), header.count, fp);
+    
+    if (read_count != (size_t)header.count) {
+        printf("读取数据时发生错误，预期 %d 条，实际读取 %zu 条。\n", header.count, read_count);
+    } else {
+        // 5. 打印读取到的内容进行验证
+        for (int i = 0; i < header.count; i++) {
+            printf("ID: %d | 书名: %-20s | 作者: %-10s | 价格: %.2f\n", 
+                    i + 1, books[i].title, books[i].author, books[i].price);
+        }
+    }
+
+    // 6. 清理工作
+    fclose(fp);
+    free(books);
+    books = NULL;
+
+    return 0;
+}

base/fwrite.c

@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct Book {
+    char title[50];
+    char author[50];
+    float price;
+};
+
+struct FileHeader {
+    char magic[4];
+    int version;
+    int count;
+};
+
+int main() {
+    int num_books = 5;
+    struct Book *books = (struct Book *)malloc(num_books * sizeof(struct Book));
+    
+    memset(books, 0, num_books * sizeof(struct Book));
+
+    // 填充模拟数据
+    for (int i = 0; i < num_books; i++) {
+        sprintf(books[i].title, "C Programming Vol.%d", i + 1);
+        sprintf(books[i].author, "Author %d", i + 1);
+        books[i].price = 30.0f + i;
+    }
+
+    // 准备文件头
+    struct FileHeader header = {{'B', 'O', 'O', 'K'}, 1, num_books};
+
+    // 以二进制写入模式打开文件
+    FILE *fp = fopen("books.dat", "wb");
+    if (!fp) {
+        perror("文件打开失败");
+        free(books);
+        return 1;
+    }
+
+    // 1. 写入文件头
+    fwrite(&header, sizeof(struct FileHeader), 1, fp);
+
+    // 2. 一次性写入所有书籍数据 (效率极高)
+    fwrite(books, sizeof(struct Book), num_books, fp);
+
+    printf("二进制数据已成功保存至 books.dat\n");
+
+    fclose(fp);
+    free(books);
+    return 0;
+}