C++实验七

11——3

#include<fstream>
using namespace std;
int main()
{
ofstream file;
file.open("test1.txt",ios_base::binary);
file<<"已成功添加字符！";
file.close();
return 0;
}

11-4

#include<fstream>
#include<iostream>
using namespace std;
int main()
{
char ch;
ifstream myfile;
myfile.open("test1.txt");
while(myfile.get(ch))
cout<<ch;
myfile.close();
return 0;
}

11-7

#include<iostream>
using namespace std;
int main()
{
ios_base::fmtflags original_flags=cout.flags();//保存现在格式化设置，方便以后的恢复使用
cout<<812<<'|';
cout.setf(ios_base::left, ios_base::adjustfield);//输出格式改为右对齐
cout.width(10);//输出域宽设为10
cout<<813<<815<<'\n';
cout.unsetf(ios_base::adjustfield);//清楚setf中对齐方式的设置
cout.precision(2);//以小数点后保留2位输出，遵循四舍五入
cout.setf(ios_base::uppercase|ios_base::scientific);//科学格式显示 E，更改了浮点数的显示格式
cout<<831.0;
cout.flags(original_flags);//恢复最初保存的格式化设置
return 0;
}

#include<iostream>
#include<fstream>
#include<string>
#include<ctime>
#include<cstdlib>
const int M=83;
using namespace std;
struct stu{
int num;
string xh, xm,bj;
};
int main()
{
string bb;
stu s[M];
char y;
while(cin>>bb)
{
ifstream is(bb.c_str());
if(!is)
{
  cout<<"error"<<endl;
  exit(1);
}
   int i=0;
   int j,a;
   while(is>>s[i].num>>s[i].xh>>s[i].xm>>s[i].bj)
   {
   i++;
   }

     ofstream os("text2.txt");
   srand(time(NULL));
   cout<<"抽取学生？"<<endl;
   while(cin>>y&&y=='Y')
   {
   a=rand()%i+1;
   cout<<s[a].num<<" "<<s[a].xh<<" "<<s[a].xm<<" "<<s[a].bj<<" "<<endl;
   os<<s[a].num<<" "<<s[a].xh<<" "<<s[a].xm<<" "<<s[a].bj<<" "<<endl;

    }

is.close();
os.close();}
return 0;
}

#include<iostream>
#include<string>
#include<fstream>
using namespace std;
int main()
{
    string bb;
    cin >> bb;
    ifstream is(bb.c_str());
     if (!is) {
         cout << "error" << endl;
         exit(1);
     }
     int li = 1, wo = 0, ch = 0;
     char c;
     while (is.get(c))
     {
             ch++;
             if ((c < 'A' || c > 'Z'&&c < 'a' || c > 'z')&&c!='\n')
                 ++wo;
             if (c == '\n')
                 ++li;
     }
     char a;
     cout<<"查看字符数：a"<<endl<<"查看单词数：b"<<endl<<"查看行数：c"<<endl;
while(cin>>a)
{
switch(a){
  case 'a':
   cout << "字符数：" << ch << endl;
   continue;
  case 'b':
       cout << "单词数：" << wo << endl;
    continue;
   case 'c':
       cout << "行数：" << li<<endl;
    continue;
   }
   }
     is.close();
     return 0;
}