标签:unknown ++ 浮点 precision src prime hit etl tin
#include<iostream> using namespace std; void main() { char ch; cout << "Type, and I shall repeat.\n"; cin.get(ch); while(ch != ‘.‘) { if (ch == ‘\n‘) cout << ch; else cout << ++ch; cin.get(ch); } system("pause"); }
#include<iostream> using namespace std; const int Size = 6; void main() { float naaq[Size]; int i = 0; float temp; cout << "First value:"; cin >> temp; while (i < Size&&temp >= 0) { naaq[i] = temp; ++i; if (i<Size) { cout << "Next value:"; cin >> temp; } } if (0 == i) cout << "No data!" << endl; else { cout << "Enter your NAAQ:"; float you; cin >> you; int count = 0; for (int j = 0; j < i; j++) { if (naaq[j] > you) ++count; } cout << count << "个数字比你的大" << endl; } system("pause"); }
#include<iostream> #include<cctype> using namespace std; void main() { cout << "Enter text for analysis,and type @ to terminate input."<<endl; char ch; int space = 0, digit = 0, chars = 0, punct = 0, others = 0; cin.get(ch); while (ch!=‘@‘) { if (isalpha(ch)) chars++; else if (isspace(ch)) space++; else if (isdigit(ch)) digit++; else if (ispunct(ch)) punct++; else others++; cin.get(ch); } cout << chars << " letters," << space << " whitespace," << digit << " digit," << punct << " punctuations," << others << " others." << endl; system("pause"); }
#include<iostream> using namespace std; const int Max = 5; void main() { double fish[Max]; cout << "Enter the weights of your fish.\nYou may enter up to " << Max << " fish<q to terminate>." << endl; cout << "fish #1: "; int i = 0; while (i<Max&&cin >> fish[i]) { if (++i < Max) cout << "fish #" << i + 1 << ": ";//i+1和++i不同,i+1对i的值没有影响 } double total = 0.0; for (int j = 0; j < i; j++)//i=5 total += fish[j]; if (i == 0) cout << "No fish!" << endl; else cout << total / i << "=average weight of " << i << " fish" << endl; system("pause"); }
根据自己的习惯重新编写
#include<iostream> using namespace std; const int Max = 5; void main() { double fish[Max],sum=0; cout << "Enter the weights of your fish.\nYou may enter up to " << Max << " fish<q to terminate>." << endl; int i; for (i = 0; i < Max; i++) { cout << "fish #" << i + 1 << ": "; if (cin >> fish[i])//输入成功返回true sum += fish[i]; else break; } if (i == 0) cout << "No fish!" << endl; else cout << sum/i<< "=average weight of " << i << " fish" << endl; system("pause"); }
#include<iostream> using namespace std; const int Max = 5; void main() { double golf[Max],sum=0; cout << "Enter your golf scores.\nYou must enter " << Max << " rounds." << endl; int i; for (i = 0; i < Max; i++) { cout << "round #" << i + 1 << ": "; while (!(cin>>golf[i])) { cin.clear(); while (cin.get() != ‘\n‘) continue; cout << "Please enter a number:"; } sum += golf[i]; } cout << sum/Max<< "=average score " <<Max<< " rounds" << endl; system("pause"); }
//文件输出(对程序而言)
#include<iostream> #include<fstream> using namespace std; void main() { char automobile[50]; int year; double a_price, d_price; //声明ofstream对象并将其同文件关联起来 ofstream outFile; outFile.open("first.txt"); cout << "Enter the make and model of automobile:"; cin.getline(automobile, 50);//cin.getline:不断读取,直到遇到换行符(少于50个字符),在末尾加上一个空字符,换行符被丢弃 cout << "Enter the model year:"; cin >> year; cout << "Enter the original asking price:"; cin >> a_price; d_price = 0.913*a_price; cout << fixed;//表示用一般的方式输出浮点数,比如num=0.00001,cout输出为1e-005,加了fixed后再输出就为0.000010 cout.precision(2);//第一位精确,第二位四舍五入,比如num = 318.15,precision(2)为3.2e+02,precision(4)为318.2 cout.setf(ios_base::showpoint);//强制显示小数点 cout << "Make and model: " << automobile << endl; cout << "Year: " << year << endl; cout << "Was asking $" << a_price << endl; cout << "Now asking $" << d_price << endl; outFile << fixed; outFile.precision(2); outFile.setf(ios_base::showpoint); outFile << "Make and model: " << automobile << endl; outFile << "Year: " << year << endl; outFile << "Was asking $" << a_price << endl; outFile << "Now asking $" << d_price << endl; outFile.close(); system("pause"); }
//文件读入(对程序而言)
#include<iostream> #include<fstream>//文件I/O #include<cstdlib>//exit() using namespace std; const int SIZE = 90; void main() { char filename[SIZE]; ifstream inFile;//声明ifstream对象 cout << "Enter name of data file:"; cin.getline(filename, SIZE); inFile.open(filename);//关联文件 if (!inFile.is_open())//文件打开失败 { cout << "Could not open the file " << filename << endl; exit(EXIT_FAILURE); } double value, sum = 0.0; int count = 0; inFile >> value; while (inFile.good())//输入正确 { ++count; sum += value; inFile >> value; } if (inFile.eof()) cout << "End of file reached." << endl; else if (inFile.fail()) cout << "Input terminated by data misamatch." << endl; else cout << "Input terminated for unknown reason." << endl; if (count == 0) cout << "No data processed." << endl; else { cout << "Items read: " << count << endl; cout << "Sum: " << sum << endl; cout << "Average: " << sum / count << endl; } inFile.close(); system("pause"); }
要想正确运行,首先在源代码文件夹中创建一个包含double数字的文本文件。
为何会少了最后一个数字17.5呢?
在文本文件中,输入最后的文本17.5后应该按下回车键,然后再保存文件。
[C++ Primer Plus] 7、分支语句和逻辑运算符(一)程序清单
标签:unknown ++ 浮点 precision src prime hit etl tin
原文地址:http://www.cnblogs.com/little-monkey/p/7509597.html