20240301作业

1.使用fwrite、fread将一张随意的bmp图片，修改成德国的国旗

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
int main(int argc, const char *argv[])
{FILE* fp = fopen("./gaoda.bmp","r");fseek(fp,2,SEEK_SET);int bmp_size = 0;fread(&bmp_size,4,1,fp);printf("文件大小为 %d 字节\n",bmp_size);int w = 0,h = 0;fseek(fp,18,SEEK_SET);fread(&w,4,1,fp);fread(&h,4,1,fp);printf("图像尺寸为:%d * %d\n",w,h);fclose(fp);fp = fopen("./gaoda.bmp","r+");fseek(fp,54,SEEK_SET);// bmp 图片默认像素格式是 bgr的unsigned char yel[3] = {0,255,255};unsigned char red[3] = {0,0,255};unsigned char bla[3] = {0,0,0};for(int i=0;i<w;i++){for(int j=0;j<(h/3);j++){fwrite(yel,3,1,fp);}}for(int i=0;i<w;i++){for(int j=(h/3);j<(h/3*2);j++){fwrite(red,3,1,fp);}}for(int i=0;i<w;i++){for(int j=(h/3*2);j<h;j++){fwrite(bla,3,1,fp);}}fclose(fp);return 0;
}

2.使用提供的getch函数，编写一个专门用来输入密码的函数，要求输入密码的时候，显示 * 号，输入回车的时候，密码输入结束

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <assert.h>
int getch() 
{int c = 0;struct termios org_opts, new_opts;int res = 0;res = tcgetattr(STDIN_FILENO, &org_opts);assert(res == 0);new_opts = org_opts;new_opts.c_lflag &= ~(ICANON | ECHO);tcsetattr(STDIN_FILENO, TCSANOW, &new_opts);c = getchar();res = tcsetattr(STDIN_FILENO, TCSANOW, &org_opts);assert(res == 0);return c;
}
void password()
{char arr[6]={'1','2','3','4','5','6'};char pass[32]={0};int i=0;printf("请输入密码:");while(1){char c=getch();if(c=='\n'){break;}printf("*");pass[i++]=c;}int a=1;for(i=0;i<6;i++){int k=strlen(pass);if(k!=6){a=0;break;}else if(pass[i]!=arr[i]){a=0;break;}}    if(a){printf("\n密码正确\n");}else{    printf("\n密码错误，请重新输入:\n");password();}fflush(stdin);
}
int main(int argc, char *argv[])
{password(); return 0;
}