本文详细介绍了使用C和C++编程语言解决一系列基础习题的方法，包括输入输出流操作、三角形面积计算、数值对齐输出、字母图形绘制、文件操作、一元二次方程求根、类的命名空间应用等。通过实例代码展示，旨在帮助读者巩固编程基础。
最近要复习一下C和C++的基础知识，于是计划把之前学过的谭浩强的《C程序设计》和《C++程序设计》习题重新做一遍。
编译环境为：操作系统32位Win7，编译工具VC++6.0
第十三章：输入输出流
10.1）输入三角形的三边边长a、b、c，通过海伦公式计算三角形面积，用cerr输出有关出错的信息
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
double a, b, c, s, area;
cin >> a >> b >> c;
if(a <= 0 || b <= 0 || c <= 0)
{
cerr << "三角形每个边长应大于0" << endl;
}
else if(a + b <= c || a + c <= b || b + c <= a)
{
cerr << "三角形两边之和须大于第三边" << endl;
}
else
{
s = (a + b + c) / 2.0;
area = sqrt(s * (s - a) * (s - b) * (s - c));
cout << "Area: " << area << endl;
}
return 0;
}10.2）从键盘输入一批数值，要求保留3位小数，在输出时上下行小数点对齐
#include<iostream>
using namespace std;
int main()
{
cout.setf(ios :: right); //右对齐
cout.setf(ios :: dec); //十进制
cout.setf(ios :: showpos); //对正数显示+号
cout.setf(ios :: fixed); //浮点数以定点格式输出
double a;
while(true)
{
cout.precision(3); //实数精度3位
cout.width(20); //字段宽度10位
cout.fill(' '); //填充字符为' '
cin >> a;
cout << a << endl;
}
cout.unsetf(ios :: right); //取消右对齐
cout.unsetf(ios :: dec); //取消十进制
cout.unsetf(ios :: showpos); //取消对正数显示+号
cout.unsetf(ios :: fixed); //取消浮点数以定点格式输出
return 0;
}10.3）编程序，在显示屏上显示一个字母B组成的三角形
#include<iostream>
using namespace std;
int main()
{
int i, j;
for(i = 0; i < 8; i++)
{
//cout << i << ":";
for(j = 8 - i - 1; j > 0; j--)
{
cout.put(' ');
}
for(j = 0; j < i * 2 + 1; j++)
{
cout.put('B');
}
cout << endl;
}
return 0;
}10.4）建立两个磁盘文件f1.dat和f2.dat
1：从键盘键入20个整数，分别存在两个磁盘文件中，每个文件存10个
2：从f1.dat中读取10个数放在f2.dat的后面
3：对f2.dat中的20个整数进行排序
#include<iostream>
#include<fstream>
#include<cstdlib>
using namespace std;
int main()
{
int a[20], i, j, temp;
//样例输入 1 3 5 7 9 11 13 15 17 19 18 16 14 12 10 8 6 4 2 0
cout << "请输入20个整数：";
//输入10个数存入f1.dat
ofstream outfile1("f1.dat", ios :: out);
if(!outfile1)
{
cerr << "f1.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 10; i++)
{
cin >> a[i];
outfile1 << a[i] << " ";
}
outfile1.close();
//输入10个数存入f2.dat
ofstream outfile2("f2.dat", ios :: out);
if(!outfile2)
{
cerr << "f2.dat 打开错误" << endl;
exit(1);
}
for(i = 10; i < 20; i++)
{
cin >> a[i];
outfile2 << a[i] << " ";
}
outfile2.close();
//从f1.dat中读入10个数存到f2.dat后
ifstream infile1("f1.dat", ios :: in);
if(!infile1)
{
cerr << "f1.dat 打开错误" << endl;
exit(1);
}
ofstream outfile3("f2.dat", ios :: out | ios :: app);
if(!outfile3)
{
cerr << "f2.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 10; i++)
{
infile1 >> temp;
outfile3 << temp << " ";
}
infile1.close();
outfile3.close();
//将f2.dat中的20个数排序后写回
//读取20个数
ifstream infile2("f1.dat", ios :: in);
if(!infile2)
{
cerr << "f1.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 20; i++)
{
infile2 >> a[i];
}
infile2.close();
//排序
for(i = 0; i < 20; i++)
{
for(j = i + 1; j < 20; j++)
{
if(a[i] > a[j])
{
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
}
//将排序后的数字写回
ofstream outfile4("f2.dat", ios :: out);
if(!outfile4)
{
cerr << "f2.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 20; i++)
{
outfile4 << a[i] << " ";
}
outfile4.close();
return 0;
}10.5）编程实现下列功能
1：按职工号大小由小到大顺序将5个员工的数据（包括号码、姓名、年龄、工资）输出到磁盘文件中保存
2：从键盘输入两个员工数据，增加到文件末尾
3：从键盘键入一个号码，从文件中查找数据，如果有则输出职工数据，没有则输出“查无此人”
#include<iostream>
#include<fstream>
#include<cstdlib>
#include<string>
using namespace std;
//职工
struct Person
{
int m_Id;
string m_Name;
int m_Age;
int m_Wage;
Person(int i, string n, int a, int w): m_Id(i), m_Name(n), m_Age(a), m_Wage(w) { }
void PrintInfo()
{
cout << "===================" << endl;
cout << "Id:\t" << this -> m_Id << endl;
cout << "Name:\t" << this -> m_Name << endl;
cout << "Age:\t" << this -> m_Age << endl;
cout << "Wage:\t" << this -> m_Wage << endl;
cout << "===================" << endl;
}
};
Person *p[5] =
{
new Person(101, "Tsybius", 23, 7100),
new Person(102, "Galatea", 21, 6600),
new Person(105, "Quintus", 15, 5000),
new Person(104, "Aurelia", 20, 8000),
new Person(103, "Julius", 30, 5050)
};
int main()
{
//对5组数据按ID进行排序
int i, j;
Person *temp;
for(i = 0; i < 5; i++)
{
for(j = i + 1; j < 5; j++)
{
if(p[i] -> m_Id > p[j] -> m_Id)
{
temp = p[i];
p[i] = p[j];
p[j] = temp;
}
}
}
//将排好序的数据存入到文件f.dat
ofstream outfile1("f.dat", ios :: out);
if(!outfile1)
{
cerr << "f.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 5; i++)
{
outfile1 << p[i] -> m_Id << " "
<< p[i] -> m_Name << " "
<< p[i] -> m_Age << " "
<< p[i] -> m_Wage << endl;
}
outfile1.close();
//再写入两个职工信息
//示例输入 108 Titus 40 4000 109 Tulius 35 5000
cout << "请输入2个职工信息：";
ofstream outfile2("f.dat", ios :: out | ios :: app);
if(!outfile2)
{
cerr << "f.dat 打开错误" << endl;
exit(1);
}
temp = new Person(0, "", 0, 0);
cin >> temp -> m_Id >> temp -> m_Name >> temp -> m_Age >> temp -> m_Wage;
outfile2 << temp -> m_Id << " "
<< temp -> m_Name << " "
<< temp -> m_Age << " "
<< temp -> m_Wage << endl;
cin >> temp -> m_Id >> temp -> m_Name >> temp -> m_Age >> temp -> m_Wage;
outfile2 << temp -> m_Id << " "
<< temp -> m_Name << " "
<< temp -> m_Age << " "
<< temp -> m_Wage << endl;
outfile2.close();
//输出文件中的全部职工数据
ifstream infile1("f.dat", ios :: in);
if(!infile1)
{
cerr << "f.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 7; i++)
{
infile1 >> temp -> m_Id >> temp -> m_Name >> temp -> m_Age >> temp -> m_Wage;
temp -> PrintInfo();
}
infile1.close();
//输入一个ID检测是否存在
int id;
cout << "请输入一个ID：";
cin >> id;
bool isFound = false;
ifstream infile2("f.dat", ios :: in);
if(!infile2)
{
cerr << "f.dat 打开错误" << endl;
exit(1);
}
for(i = 0; i < 7; i++)
{
infile2 >> temp -> m_Id >> temp -> m_Name >> temp -> m_Age >> temp -> m_Wage;
if(temp -> m_Id == id)
{
temp -> PrintInfo();
isFound = true;
break;
}
}
if(!isFound)
{
cerr << "没有找到这个人" << endl;
}
infile2.close();
return 0;
}10.6）在例13.17的基础上，修改程序，将存在在c数组中的数据读入并显示出来
#include<iostream>
#include<strstream>
using namespace std;
struct Student
{
int m_Num;
char m_Name[20];
float m_Score;
};
int main()
{
Student stud[3] = { 1001, "Li", 78, 1002, "Wang", 89.5f, 1004, "Fun", 90 };
//将信息存入到字符串中
char c[50];
ostrstream strout(c, sizeof(c));
int i;
for(i = 0; i < 3; i++)
{
strout << stud[i].m_Num << " "
<< stud[i].m_Name << " "
<< stud[i].m_Score << " ";
}
strout << ends;
cout << "array c:" << c << endl;
//从字符串中读取信息
Student stud2[3];
istrstream strin(c, sizeof(c));
for(i = 0; i < 3; i++)
{
strin >> stud2[i].m_Num >> stud2[i].m_Name >> stud2[i].m_Score;
cout << stud2[i].m_Num << " "
<< stud2[i].m_Name << " "
<< stud2[i].m_Score << endl;
}
return 0;
}第十四章：输入输出流
14.1）求一元二次方程ax^2+bx+c=0的实根，如果方程没有实根，则输出有关警告信息
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
double a, b, c, delta;
cin >> a >> b >> c;
try
{
//计算Δ
delta = b * b - 4 * a * c;
if(delta < 0)
{
throw delta;
}
//求根
double x1 = (-1 * b + sqrt(delta)) / (2 * a);
double x2 = (-1 * b - sqrt(delta)) / (2 * a);
cout << "x1=" << x1 << ";x2=" << x2 << endl;
}
catch(double)
{
//Δ<0的情况
cout << "b^2-4ac=" << delta << "<0" << endl;
cout << "方程无实根" << endl;
}
cout << "程序运行完毕" << endl;
return 0;
}14.3）在两个命名空间中实现Student类
#include<iostream>
#include<string>
using namespace std;
namespace ns1
{
struct Student
{
int m_ID;
string m_Name;
int m_Age;
string m_Addr;
//构造函数
Student(int id, string na, int ag, string ad):
m_ID(id), m_Name(na), m_Age(ag), m_Addr(ad) { }
}
stud[3] =
{
Student(101, "Tsybius", 23, "XXX"),
Student(102, "Galatea", 21, "YYY"),
Student(103, "Aurelia", 22, "ZZZ")
};
}
namespace ns2
{
struct Student
{
int m_ID;
string m_Name;
char m_Sex;
string m_Addr;
//构造函数
Student(int id, string na, char sx, string ad):
m_ID(id), m_Name(na), m_Sex(sx), m_Addr(ad) { }
}
stud[3] =
{
Student(101, "Tsybius", 'm', "XXX"),
Student(102, "Galatea", 'f', "YYY"),
Student(103, "Aurelia", 'f', "ZZZ")
};
}
int main()
{
int id;
cout << "请输入一个ID：";
cin >> id;
//搜索内容
ns1 :: Student *s1;
ns2 :: Student *s2;
for(int i = 0; i < 3; i++)
{
if(ns1 :: stud[i].m_ID == id)
{
s1 = &(ns1 :: stud[i]);
}
if(ns2 :: stud[i].m_ID == id)
{
s2 = &(ns2 :: stud[i]);
}
}
cout << "ID:\t" << s1 -> m_ID << endl;
cout << "Name:\t" << s1 -> m_Name << endl;
cout << "Age:\t" << s1 -> m_Age << endl;
cout << "Sex:\t" << s2 -> m_Sex << endl;
cout << "Addr:\t" << s1 -> m_Addr << endl;
return 0;
}END
扫一扫
353
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
