我正在尝试将中缀表达式转换为后缀表达式。例如: "20 + 2 * 3 + (2*8 + 5)* 4" ->20 2 3 * + 2 8 * 5 + 4 * + 这是我的代码:
Stack<Character> s = new Stack<Character>();
String postfix = "";
boolean enter = true;
String infixExpr = "20 + 2 * 3 + (2*8 + 5)* 4";
for(int i = 0;i<infixExpr.length();i++){
if(Character.isDigit(infixExpr.charAt(i)) == true){
postfix = postfix + infixExpr.charAt(i);
}
if(infixExpr.charAt(i) == '+' || infixExpr.charAt(i) == '-'){
if(s.isEmpty() == true){
s.push(infixExpr.charAt(i));
}
else{
if(s.peek() == '*' || s.peek() == '/' || s.peek() == '+' || s.peek() == '-'){
while(s.isEmpty()== false){
postfix = postfix + s.pop();
}
s.push(infixExpr.charAt(i));
}
else{
s.push(infixExpr.charAt(i));
}
}
}
if(infixExpr.charAt(i) == '*' || infixExpr.charAt(i) == '/' ){
if(s.isEmpty() == true){
s.push(infixExpr.charAt(i));
}
else{
if(s.peek()== '+' || s.peek() == '-' || s.peek() == '('){
s.push(infixExpr.charAt(i));
}
else if(s.peek() == '*' || s.peek() == '/'){
while(s.isEmpty()== false){
postfix = postfix + s.pop();
}
s.push(infixExpr.charAt(i));
}
}
if(infixExpr.charAt(i) == '('){
s.push(infixExpr.charAt(i));
}
if(infixExpr.charAt(i) == ')'){
while(enter){
if(s.peek() == '('){
enter = false;
}
else{
postfix = postfix + s.pop();
}
}
}
}
}
如题所述,我应该得到“20 2 3 * + 2 8 * 5 + 4 * +”,但我得到了“2023*+28*+54”,这是错误的。我已经多次检查代码,但仍然找不到问题。如果有人能帮忙解决,那就太好了。