第三章

1

#include <iostream>
using namespace std;const int number = 12;int main() {cout << "请输入你的身高，单位为英寸" << endl;int inch, feet;cin >> inch;feet = inch / number;inch = inch % number;cout << "您的身高为" << feet << "英尺" << inch << "英尺" << endl;
}

2

#include<iostream>
using namespace std;const double meter_inch = 0.0254;
const double pound_kg = 2.2;
const double inch_feet = 12;double BMI(double inch, double pound) {double meter = inch * meter_inch;double kg = pound / pound_kg;return kg / meter / meter;
}void main() {double feet, inch, pound;cout << "输入您的身高（英尺）：" << endl;cin >> feet;cout << "输入您的身高（英寸）：" << endl;cin >> inch;cout << "输入您的体重（磅）：" << endl;cin >> pound;double inch_all = inch + inch_feet * feet;double bmi = BMI(inch_all, pound);cout << "您的BMI为" << bmi << endl;}

3

#include<iostream>
using namespace std;void main() {cout << "Enter a latittude in degrees,minutes,and seconds:" << endl;cout << "First, enter the degrees:";double degrees, minutes, seconds;cin >> degrees;cout <<endl<< "Next, enter the minutes of arc:";cin >> minutes;cout << endl << "Finally, enter the seconds of arc:";cin >> seconds;cout << degrees << " degrees," << minutes << " minutes," << seconds << "= ";double degrees_final = degrees + minutes / 60 + seconds / 60 / 60;cout << degrees_final << " degrees." << endl;
}

4

#include<iostream>
using namespace std;void main() {int seconds_all;cout << "Enter the number of seconds:";cin >> seconds_all;int temp = seconds_all;int seconds = temp % 60;temp=temp/ 60;int minutes = temp % 60;temp =temp/ 60;int hours = temp % 24;temp =temp/ 24;int days = temp;cout << seconds_all << " seconds = " << days << "days, " << hours << " hours, " << minutes << " minutes, " << seconds << " seconds." << endl;
}

5

#include<iostream>
using namespace std;void main() {long long total, current;cout << "Enter the world's population:";cin >> total;cout << "Enter the population of the US:";cin >> current;double percent = (double)current / (double)total;cout << "The population of the US is " << percent << "% of the world population" << endl;
}

6

#include<iostream>
using namespace std;void main() {cout << "使用英里/加仑，请输入1" << endl << "使用公里/升，请输入2" << endl;int input;cin >> input;if (input == 1) {double miles, gallon;cout << "请输入英里数：";cin >> miles;cout << "请输入加仑数：";cin >> gallon;cout << "每加仑可行驶" << miles / gallon << "英里" << endl;}else {double km, L;cout << "请输入公里数：";cin >> km;cout << "请输入多少升：";cin >> L;cout << "每100公里耗油" << 100*km/L<< "升" << endl;}}

7

#include<iostream>
using namespace std;
const double mpg_to_lpkm = 19.0 / 12.4
const double lpkm_to_mpg = 1 / mpg_to_lpkm;void main() {cout << "请输入欧洲风格耗油量(每百公里消耗多少升）：" << endl;double n;cin >> n;cout << n * mpg_to_lpkm;
}//这个题是想考语法的，但是数学太乱了，我不考虑数学了，数学解法乱写的