上課教材

試著列印出”Hello, C++”!

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#include <iostream>    //引用iostream工具箱
using namespace std;
 
int main() {    //main是程式的起點

	cout << "Hello, C++." << endl;    //"endl"表換行
        //跟電腦說我要輸出一個字串
	return 0;
        //程式結束
}

輸入一個半徑，請問圓面積等於多少？

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#include <iostream>
using namespace std;
 
int main() {
 
	//輸入 
	int r; // Declare r as integer.
	cin >> r;
 
	//演算法
	double A 
	A = r * r * 3.14;
        /*
        double A = r * r * 3.14;
        */
    
	//輸出
	cout << A << endl;
 
	return 0;
 }

假設年初投入金額123元，年末賺到4元，問年報酬率是多少%?

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#include <iostream>
using namespace std;
 
int main() {
	int amount = 123, profit = 4;
	double return_rate = (double) profit / amount;
	cout << "Return rate(%)=" << return_rate * 100<<endl;
	//double return_rate = 100.0 * profit / amount;
	//cout << "Return rate(%)=" << return_rate <<endl;
	return 0;
}

Body Mass Index(BMI)

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using namespace std;
 
int main() {
	int name ;
	double BMI, weight, height ;
 
	cout << "輸入姓名" << endl ;
	cin >> name >> endl ;
 
	cout << "輸入身高(公分)" << endl ;
	cin >> height >> endl ;
 
	cout << "輸入體重(公斤)" << endl ;
	cin >> weight >> endl ;
 
	height=height/100;
	BMI=weight/(height*height);
	cout << name << BMI << endl ;
	return 0 ;
}

輸入一個半徑，先判斷半徑是否大於0，在執行圓面積等於多少，若小於、等於0則貼出”Not a circle. “

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#include <iostream>
using namespace std;
 
int main() {
	int r ;
	cin >> r ;
	if (r>0){
		double A = r*r*3.14;
		cout << A << endl ;
	}
	else{
		cout << "Not a circle. " << endl;
	}
	return 0;
}

飲料販賣機**

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#include <iostream>
using namespace std;
 
int main() {
	//Item:(1)coke(25)
	//     (2)black tea(30)
	//     (3)milk tea(50)
	int choice;
	cin >> choice;
	int coin;
	cin >> coin;
	int price;
	switch(choice){
		case 1:
			price = 25;
			break;
		case 2:
			price = 30;
			break;
		case 3:
			price = 50;
			break;
	}
	if (coin>=price){
		cout << "You got what you want with the changes $" 
			<< coin-price <<". "<<endl ;
	}else{
		cout <<"Insent more coin. " << endl;
	}
	return 0;
}

隨機亂數

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#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
 
int main() {
	srand(time(0));
	cout << rand()%6+1<<" ";
	return 0;
}

輾轉相除法

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#include <iostream>
using namespace std;
 
int main() {
	int a =54, b=32;
	int r;
	do {
		r=a%b;
		a=b;
		b=r;
	}while(r>0);
	cout<<a<<endl;
	return 0;
}

1+2+3+…+100=?

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#include <iostream>
using namespace std;
 
int main() {
	int s=0;
	/*
	int i=1;
	while(i<=100){
		s=s+i;
		i++;
	}
	*/
	for(int i=1;i<=100;i++){
		s=s+i;
	}
	cout<<s<<endl;
	return 0;
}