IO进程day2

一、思维导图

二、练习题1

        使用 fread 和 fwrite 将一张任意bmp图片改成德国旗

#include <stdio.h>

int main()
{
	FILE* fp=fopen("rising_freedom.bmp", "r+");
	if(NULL==fp)
	{
		perror("fopen");
		return 1;
	}

	int bmp_size=0;
	int bmp_width=0;
	int bmp_height=0;
	fseek(fp,2,SEEK_SET);
	fread(&bmp_size,4,1,fp);
	printf("图片大小为：%d\n", bmp_size);

	fseek(fp,18,SEEK_SET);
	fread(&bmp_width,4,1,fp);
	fread(&bmp_height,4,1,fp);
	printf("图片像素为：%d * %d\n", bmp_width, bmp_height);

	fseek(fp,54,SEEK_SET);
	unsigned char bgr_b[3]={0,0,0}; //黑
	unsigned char bgr_r[3]={0,0,255}; //红
	unsigned char bgr_y[3]={0,255,255}; //金黄色

	for(int i=0; i<bmp_width*(bmp_height/3); i++)
	{
		fwrite(bgr_y,3,1,fp);
	}
	for(int i=0; i<bmp_width*(bmp_height/3); i++)
	{
		fwrite(bgr_r,3,1,fp);
	}
	for(int i=0; i<bmp_width*(bmp_height/3); i++)
	{
		fwrite(bgr_b,3,1,fp);
	}

	printf("旗子绘制完成！\n");
	fclose(fp);
	return 0;
}

三、练习题修改

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

struct Data
{
	char name[20];
	double math;
	double chinese;
	double englishl;
	double physical;
	double chemical;
	double biological;
};

typedef struct Student
{
	union
	{
		struct Data data;
		struct Student* tail;
	};
	struct Student* next;
	struct Student* prev;
}stu_t;

stu_t* create_stu()
{
	stu_t* node=calloc(1,sizeof(stu_t));
	node->next=NULL;
	node->prev=NULL;
	node->tail=node;
	return node;
}

void insert_stu(stu_t* head, struct Data data)
{
	stu_t* newstu=create_stu();
	newstu->data=data;
	head->tail->next=newstu;
	newstu->next=NULL;
	newstu->prev=head->tail;
	head->tail=newstu;
}

void show(stu_t* head)
{
	stu_t* p=head->next;
	while(p!=NULL)
	{
		printf("姓名：%s\n", p->data.name);
		printf("数学：%lf\n", p->data.math);
		printf("语文：%lf\n", p->data.chinese);
		printf("英语：%lf\n", p->data.english);
		printf("物理：%lf\n", p->data.physical);
		printf("化学：%lf\n", p->data.chemical);
		printf("生物：%lf\n", p->data.biological);
		printf("-----------------------------\n");
		p=p->next;
	}
}

void save(stu_t* head, const char* filename)
{
	FILE* fp=fopen(filename,"w");
	stu_t* p=head->next;
	while(p!=NULL)
	{
		fprintf(fp,"%s %lf %lf %lf %lf %lf %lf\n", p->data.name, p->data.math, p->data.chinese, p->data.english, p->data.physical, p->data.chemical, p->data.biological);
		p=p->next;
	}
	fclose(fp);
}

void load(stu_t* head, const char* filename)
{
	FILE* fp=fopen(filename,"r");
	if(fp==NULL)
	{
		printf("文件不存在！\n");
		return;
	}
	
	while(1)
	{
		struct Data data={0};
		int res=fscanf(fp,"%s %lf %lf %lf %lf %lf %lf\n", data.name, &data.math, &data.chinese, &data.english, &data.physical, &data.chemical, &data.biological);
		if(res==EOF)
		{
			break;
		}
		insert_stu(head,data);
	}
	fclose(fp);
}

int main()
{
	stu_t* head=create_stu();
	struct Data d1={"张三",99,99,99,99,99,99};
	struct Data d2={"李四",88,88,88,88,88,88};
	struct Data d3={"王五",77,77,77,77,77,77};
	insert_stu(head, d1);
	insert_stu(head, d2);
	insert_stu(head, d3);
	save(head,"stu.txt");
	stu_t* head2=create_stu();
	load(head2,"stu.txt");
	show(head2);
	return 0;
}