2-12

C Crash Course/21 Input&Output/prelesson/binary file/fwrite/student information/main.c

@@ -0,0 +1,66 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include "student.h"
+
+void getList(Student* Stu, int num);
+int save(Student* Stu, int num);
+
+int main(void) {
+
+	int num = 0;
+
+	printf("请输入学生数量：\n");
+	scanf("%d", &num);
+	Student* Stu = (Student*)malloc(sizeof(Student) * num);
+
+	getList(Stu, num);
+
+	if (save(Stu, num)) {
+		printf("保存成功\n");
+	}
+	else
+		printf("保存失败\n");
+
+	return 0;
+}
+
+void getList(Student* Stu, int num) {
+
+	char format[STR_LEN];
+	sprintf(format, "%%%ds", STR_LEN - 1);
+	//向 format 中写入 %19s
+	//%%%ds 前两个%的意义是写入% 
+	//%d 输出后面的参数，即：19 
+	//最终写入的就是 %19s
+
+	int i = 0;
+
+	for (i = 0; i < num; i++) {
+
+		printf("第 %d 个学生 \n", i + 1);
+		printf("\t姓名：");
+		scanf(format, Stu[i].name);
+		printf("\t性别（0-男 1-女 2-其他）:");
+		scanf("%d", &Stu[i].gender);
+		printf("\t年龄:");
+		scanf("%d", &Stu[i].age);
+		//记得用scanf时，何时用 & 
+	}
+
+}
+
+int save(Student* Stu, int num) {
+
+	int ret = -1;
+	FILE* fp = fopen("student.data", "wx");
+	if (fp) {
+		ret = fwrite(Stu, sizeof(Student), num, fp);
+		//记录 fwrite 的返回值：写入文件的学生个数
+		fclose(fp);
+	}
+	else
+		printf("文件打开失败！");
+
+	return (ret == num);
+	//如果写入的个数不等于总人数，返回0
+}

C Crash Course/21 Input&Output/prelesson/binary file/fwrite/student information/readme.md

@@ -0,0 +1,4 @@
+程序中向文件中写入2进制文本
+
+linux 下可以用 `od` 命令打开文件
+

C Crash Course/21 Input&Output/prelesson/binary file/fwrite/student information/student.h

@@ -0,0 +1,11 @@
+#ifndef _STUDENT_H_
+#define _STUDENT_H_
+
+#define STR_LEN  20
+
+typedef struct _student {
+	char name[STR_LEN];
+	char gender;
+	char age;
+}Student;
+#endif