第七章作业

系统管理员 2022-08-01 01:21 198阅读 0赞

第七章  作业

1、1.\#include <iostream>  
\#include <cmath>  
using namespace std;  
void area(float a,float b,float c)  
\{  
 double s,area;  
 if(a+b<=c)  
  cerr<<"a+b<=c,error!"<<endl;  
 else if(b+c<=a)  
  cerr<<"b+c<=a,error!"<<endl;  
 else if(a+c<=b)  
  cerr<<"a+c<=b,error!"<<endl;  
 else  
 \{  
  s=(a+b+c)/2;  
  area=sqrt(s\*(s-a)\*(s-b)\*(s-c));  
  cout<<"area="<<area<<endl;  
 \}  
\}  
int main()  
\{  
 float a=4,b=6,c=7;  
 area(a,b,c);  
 return 0;  
\}![Center][]

2、 \#include <iostream>  
using namespace std;  
int main()  
\{  
 float a\[5\];  
 int i;  
 cout<<"input number:";  
 for(i=0;i<5;i++)  
  cin>>a\[i\];  
 cout.setf(ios::fixed);  
 cout.precision(3);  
 for(i=0;i<5;i++)  
 \{  
  //cout.width(10);  
  cout<<a\[i\]<<endl;  
 \}  
 return 0;  
\}

![Center 1][]

3. \#include <iostream>  
\#include <iomanip>  
using namespace std;  
int main()  
\{  
 for(int i=1;i<8;i++)  
cout<<setw(20-i)<<setfill(' ')<<" "<<setw(2\*i-1)<<setfill('B')<<"B"<<endl;    
 return 0;  
\}

![Center 2][]

4. \#include <iostream>  
\#include <fstream>  
using namespace std;  
void fun1()  
\{  
 int a\[10\];  
 ofstream outfile1("f1.data",ios::out),outfile2("f2.data",ios::out);  
 if(!outfile1)  
 \{  
  cerr<<"open error!"<<endl;  
  exit(1);  
 \}  
 if(!outfile2)  
 \{  
  cerr<<"open error!"<<endl;  
  exit(1);  
 \}  
 cout<<"input 10 integer numbers:"<<endl;  
 for(int i=0;i<10;i++)  
 \{  
  cin>>a\[i\];  
  outfile1<<a\[i\]<<" ";  
 \}  
 cout<<"input 10 integer numbers:"<<endl;  
 for(i=0;i<10;i++)  
 \{  
  cin>>a\[i\];  
  outfile2<<a\[i\]<<" ";  
 \}  
 outfile1.close();  
 outfile2.close();  
\}  
void fun2()  
\{  
 ifstream infile("f1.data");  
 if(!infile)  
 \{  
cerr<<"open error!"<<endl;  
    exit(1);  
 \}  
 ofstream outfile("f2.data",ios::app);  
 if(!outfile)  
 \{  
    cerr<<"open error!"<<endl;  
exit(1);  
 \}  
 int a;  
 for(int i=0;i<10;i++)  
 \{  
  infile>>a;  
  outfile<<a<<" ";  
 \}  
 infile.close();  
 outfile.close();  
\}  
void fun3()  
\{  
 ifstream infile("f2.data");  
 if(!infile)  
 \{  
  cerr<<"open error!"<<endl;  
  exit(1);  
 \}  
 int a\[20\];  
 int i,j,t;  
 for(i=0;i<20;i++)  
infile>>a\[i\];  
 for(i=0;i<20;i++)  
for(j=i+1;j<20;j++)  
if(a\[i\]>a\[j\])  
\{t=a\[i\];a\[i\]=a\[j\];a\[j\]=t;\}  
 infile.close();  
 ofstream outfile("f2.data",ios::out);  
 if(!outfile)  
 \{  
   cerr<<"open error!"<<endl;  
  exit(1);  
 \}  
 cout<<"data in f2.data:"<<endl;  
 for(i=0;i<20;i++)  
 \{  
  outfile<<a\[i\]<<" ";  
  cout<<a\[i\]<<" ";  
 \}  
 cout<<endl;  
 outfile.close();  
\}  
int main()  
\{  
 fun1();  
 fun2();  
 fun3();  
 return 0;  
\}

5. \#include <iostream>  
\#include <fstream>  
using namespace std;  
struct staff  
\{  
 int num;  
 char name\[10\];  
 int age;  
 double pay;  
\};  
int main()  
\{  
staff s\[7\]=\{1,"xiong",18,10000,3,"xian",18,20000,2,"piao",26,20000,4,"xin",26,10000,5,"xun",20,15000\},s1;  
    fstream iofile("staff.dat",ios::in|ios::out|ios::binary);  
    if(!iofile)  
\{  
cerr<<"open error!"<<endl;  
abort();  
\}  
int i,m,num;  
cout<<"Five staff:"<<endl;  
for(i=0;i<5;i++)  
\{  
cout<<s\[i\].num<<" "<<s\[i\].name<<" "<<s\[i\].age<<" "<<s\[i\].pay<<endl;  
iofile.write((char \*)&s\[i\],sizeof(s\[i\]));  
\}  
cout<<"Please insert two staff's message:"<<endl;  
for(i=0;i<2;i++)  
\{cin>>s1.num>>s1.name>>s1.age>>s1.pay;  
iofile.seekp(0,ios::end);  
iofile.write((char \*)&s1,sizeof(s1));\}  
iofile.seekg(0,ios::beg);  
for(i=0;i<7;i++)  
\{iofile.read((char \*)&s\[i\],sizeof(s\[i\]));  
cout<<s\[i\].num<<" "<<s\[i\].name<<" "<<s\[i\].age<<" "<<s\[i\].pay<<endl;\}  
bool find;  
cout<<"enter number you want to search,enter 0 to stop";  
cin>>num;  
while(num)  
\{  
find=false;  
iofile.seekg(0,ios::beg);  
for(i=0;i<7;i++)  
\{  
 iofile.read((char \*)&s\[i\],sizeof(s\[i\]));  
 if(num==s\[i\].num)  
 \{  
  m=iofile.tellg();  
  cout<<num<<"is NO."<<m/sizeof(s1)<<endl;  
  cout<<s\[i\].num<<" "<<s\[i\].name<<" "<<s\[i\].age<<" "<<s\[i\].pay<<endl;  
  find=true;  
  break;  
 \}  
\}  
if(!find)  
cout<<"can't find!"<<num<<endl;  
cout<<"please input again!";  
cin>>num;  
\}  
iofile.close();  
return 0;  
\}

6. \#include <iostream>  
\#include <strstream>  
using namespace std;  
//struct staff  
struct student  
\{  
 int num;  
 char name\[10\];  
 //int age;  
 //double pay;  
 double score;  
\};  
int main()  
\{  
student stud\[3\]=\{1001,"Li",78,1002,"Wang",89.5,1004,"Fun",90\},stud1\[3\];  
    char c\[50\];  
int i;  
ostrstream strout(c,50);  
for(i=0;i<3;i++)  
strout<<stud\[i\].num<<" "<<stud\[i\].name<<" "<<stud\[i\].score<<" ";  
strout<<ends;  
cout<<"array c:"<<endl<<c<<endl<<endl;  
istrstream strin(c,50);  
for(i=0;i<3;i++)  
strin>>stud1\[i\].num>>stud1\[i\].name>>stud1\[i\].score;  
cout<<"data from array c to arry s1:"<<endl;  
for(i=0;i<3;i++)  
cout<<stud\[i\].num<<" "<<stud\[i\].name<<" "<<stud\[i\].score<<endl;  
cout<<endl;  
return 0;  
\}

[Center]: /images/20220801/4f2b57f324404c7cb76a215eae834e52.png
[Center 1]: /images/20220801/65ecc5490d2b481b98fdfd64812acfe6.png
[Center 2]: /images/20220801/04ad73a9a7ea4238ad79477afbe52acf.png