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#include 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
#includeusing 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
#includeusing 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#include #include 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#include #include #include 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#include 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#include 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#include 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;}
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