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2025-01-13 用栈实现计算器

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liangjinglin 2025-01-14 00:29:45 +08:00
parent ca2ce0d684
commit 6c51073f51
1 changed files with 134 additions and 0 deletions
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src/dataANDcalc/java/stack/CalculatorByStack.java Normal file
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package stack;
import java.util.Scanner;
import java.util.regex.Pattern;
public class CalculatorByStack {
private final static int ADD = 1;
private final static int SUB = 2;
private final static int MUL = 3;
private final static int DIV = 4;
private ArrayStack numStack = new ArrayStack(10);
private ArrayStack operStack = new ArrayStack(10);
public void calculate(String expression) {
int length = expression.length();
for (int i = 0; i<length;i++){
String str = expression.substring(i,i+1);
String operRegex = "[+\\-*/]";
Pattern operPattern = Pattern.compile(operRegex);
if (operPattern.matcher(String.valueOf(str)).matches()) {
if("+".equals(str)){
if(operStack.isEmpty()){
operStack.push(ADD);
continue;
}
cal();
operStack.push(ADD);
}
if("-".equals(str)){
if(operStack.isEmpty()){
operStack.push(SUB);
continue;
}
cal();
operStack.push(SUB);
}
if("*".equals(str)){
if(operStack.isEmpty() || operStack.top() < 3){
operStack.push(MUL);
continue;
}
cal();
operStack.push(MUL);
}
if("/".equals(str)){
if(operStack.isEmpty() || operStack.top() < 3){
operStack.push(DIV);
continue;
}
cal();
operStack.push(DIV);
}
}else {
int num = Integer.parseInt(str);
numStack.push(num);
}
}
// 开始进行计算
while (true) {
if(numStack.isEmpty()){
System.out.println("当前无计算公式");
}
if(numStack.getTop() == 0){
System.out.println("计算结果为:" + numStack.pop());
break;
}
cal();
}
}
public void cal(){
int oper = operStack.pop();
if(oper == ADD){
int num1 = numStack.pop();
int num2 = numStack.pop();
int result = num1 + num2;
numStack.push(result);
}
if(oper == SUB){
int num1 = numStack.pop();
int num2 = numStack.pop();
int result = num2 - num1;
numStack.push(result);
}
if(oper == MUL){
int num1 = numStack.pop();
int num2 = numStack.pop();
int result = num2 * num1;
numStack.push(result);
}
if(oper == DIV){
int num1 = numStack.pop();
int num2 = numStack.pop();
int result = num2/num1;
numStack.push(result);
}
}
private void show(){
System.out.println("数栈数据:");
numStack.show();
System.out.println("符号栈数据:");
operStack.show();
}
public static void main(String[] args) {
CalculatorByStack calcStack = new CalculatorByStack();
Scanner scan = new Scanner(System.in);
while (true) {
System.out.println("c计算, s查看, exit退出:");
String handle = scan.next();
if ("exit".equals(handle)){
break;
}
if ("c".equals(handle)){
System.out.println("请输入计算表达式:");
String expression = scan.next();
calcStack.calculate(expression);
}
if ("s".equals(handle)){
calcStack.show();
}
}
scan.close();
}
}