使用Java的基本计算器程序
基本计算器能够对两个数字进行加，减，乘或除运算。这是使用开关盒完成的。演示此的程序如下所示-
示例
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
double num1;
double num2;
double ans;
char op;
Scanner reader = new Scanner(System.in);
System.out.print("Enter two numbers: ");
num1 = reader.nextDouble();
num2 = reader.nextDouble();
System.out.print("\nEnter an operator (+, -, *, /): ");
op = reader.next().charAt(0);
switch(op) {
case '+': ans = num1 + num2;
break;
case '-': ans = num1 - num2;
break;
case '*': ans = num1 * num2;
break;
case '/': ans = num1 / num2;
break;
default: System.out.printf("Error! Enter correct operator");
return;
}
System.out.print("\nThe result is given as follows:\n");
System.out.printf(num1 + " " + op + " " + num2 + " = " + ans);
}
}输出结果
Enter two numbers: 10.0 7.0 Enter an operator (+, -, *, /): - The result is given as follows: 10.0 - 7.0 = 3.0
现在让我们了解上面的程序。
从用户处获得两个数字以及运算符。证明这一点的代码片段如下-
double num1;
double num2;
double ans;
char op;
Scanner reader = new Scanner(System.in);
System.out.print("Enter two numbers: ");
num1 = reader.nextDouble();
num2 = reader.nextDouble();
System.out.print("\nEnter an operator (+, -, *, /): ");
op = reader.next().charAt(0);开关盒用于对两个数字执行指定的操作。如果输入的运算符不正确，则会显示错误消息。证明这一点的代码片段如下所示-
switch(op) {
case '+': ans = num1 + num2;
break;
case '-': ans = num1 - num2;
break;
case '*': ans = num1 * num2;
break;
case '/': ans = num1 / num2;
break;
default: System.out.printf("Error! Enter correct operator");
return;
}最后，打印结果。证明这一点的代码片段如下所示-
System.out.print("\nThe result is given as follows:\n");
System.out.printf(num1 + " " + op + " " + num2 + " = " + ans);