标准IO

1.思维导图

2.使用 fread 和 fwrite 函数，重写昨天的第2个作业

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct student
{
	char name[10];
	int chinese;
	int math;
	int English;
	int physics;
	int chemistry;
	int biology;
}stu,*stuptr;
typedef struct node
{
	union
	{
		stu data;
		int len;
	};
	struct node* next;
}node,*nodeptr;
nodeptr creat_head()
{
	nodeptr h = (nodeptr)malloc(sizeof(node));
	if(NULL == h)
	{
		printf("创建失败\n");
		return NULL;
	}
	h->len = 0;
	h->next = NULL;
	return h;
}
nodeptr node_creat(stu arr)
{
	nodeptr p = (nodeptr)malloc(sizeof(node));
	if(NULL==p)
	{
		printf("创建失败\n");
		return NULL;
	}
	p->data=arr;
	p->next=NULL;
	return p;
}
int node_add(stu arr,nodeptr h)
{
	if(NULL==h)
	{
		printf("插入失败\n");
		return 0;
	}
	nodeptr p=node_creat(arr);
	p->next=h->next;
	h->next=p;
	h->len++;
	return 1;
}
int show(nodeptr h)
{
	if(NULL==h)
	{
		printf("遍历失败\n");
		return 0;
	}
	nodeptr p=h;
	while(p->next!=NULL)
	{
		p=p->next;
		printf("姓名：%s\n",p->data.name);
		printf("语文：%d\n",p->data.chinese);
		printf("数学：%d\n",p->data.math);
		printf("英语：%d\n",p->data.English);
		printf("物理：%d\n",p->data.physics);
		printf("化学：%d\n",p->data.chemistry);
		printf("生物：%d\n",p->data.biology);
		printf("------------------------\n");
	}
}
int save(nodeptr h)
{
	if(NULL==h)
	{
		printf("失败\n");
		return 0;
	}
	FILE* fp = fopen("student.text","w");
	nodeptr p=h;
	for(int i=0;i<3;i++)
	{
		p=p->next;
		fwrite(&p->data,sizeof(stu),1,fp);
	}
	fclose(fp);
	return 1;
}
int load(nodeptr p)
{
	FILE* fp = fopen("student.text","r");
	while(1)
	{
		stu brr={0};
		int res=fread(&brr,sizeof(stu),1,fp);
		if(res==0){break;}
		node_add(brr,p);
	}
	fclose(fp);
	return 1;
}

int main(int argc, const char *argv[])
{
	nodeptr h=creat_head();
	stu arr1={"chen",99,88,99,88,98,88};
	stu arr2={"yu",99,98,99,78,98,88};
	stu arr3={"lin",99,88,99,98,98,98};
	node_add(arr1,h);
	node_add(arr2,h);
	node_add(arr3,h);
	save(h);
	

	nodeptr b=creat_head();
	load(b);
	show(b);
	show(h);
	return 0;
}

结果

3.使用 fread 和 fwrite 将一张任意bmp图片改成德国国旗

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, const char *argv[])
{
	FILE* fp = fopen("gaoda.bmp","r+");
	if(NULL==fp)
	{
		perror("fopen");
		return 0;
	}
	int bmp_size=0,bmp_width=0,bmp_height=0;
	fseek(fp,18,SEEK_SET);
	fread(&bmp_width,4,1,fp);
	fread(&bmp_height,4,1,fp);
	

    int size=bmp_height*bmp_width;
	fseek(fp,54,SEEK_SET);
	unsigned char yellow[3] ={0,255,255};
	unsigned char red[3]={0,0,255};
	unsigned char black[3]={0,0,0};
	for(int i=0;i<size;i++)
	{
		if(i>=0&&i<size/3)
		{
			fwrite(yellow,3,1,fp);
		}

		else if(i>=size/3&&i<2*size/3)
		{
			fwrite(red,3,1,fp);
		}
		 else if(i>=2*size/3&&i<size)
		{
			fwrite(black,3,1,fp);
		}
	}
	fclose(fp);
	return 0;
}