[英]How to output an arithmetic expression with unary operator?
我有一個帶有一元運算符的算術表達式(字符串),我想將每個元素放入數組中。 例如:-3 + 4.2 * 5 ==>輸出應為:-3,+,4.2,*,5(不是-,3,+,4.2,*,5)3 + -5 ==>輸出應為:3,+,-5(使用一元運算符)(3 /(5-8)+18) 2 ==>輸出應為:(,3,/,(,5,-,8,),+, 18,) ,,2
這是到目前為止我嘗試過的代碼,其輸出為3,+,-,5,這沒有將一元運算符放在數字的前面。
我的問題是如何將每個元素正確地放置在數組中。
public class Test2 {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
System.out.println("Input:");
Scanner in = new Scanner(System.in);
String input = in.nextLine();
String[] arr1= splitInfixExpression(input);
for(int i=0;i<arr1.length;i++)
{
System.out.println(arr1[i]);
}
}
priva te static boolean isOperandChar(final char c) {
return Character.isDigit(c) || c == '.';
}
private static boolean isParenthesis(final char c) {
return c=='('||c==')';
}
private static String[] splitInfixExpression(final String input) {
final List<String> postfixExpression = new ArrayList<>();
boolean encounteredOperandStart = false;
String currentOperand = "";
for (final char c : input.toCharArray()) {
if (encounteredOperandStart) {
if (isOperandChar(c)) {
currentOperand += c;
}
postfixExpression.add(currentOperand);
postfixExpression.add(String.valueOf(c));
currentOperand = "";
encounteredOperandStart = false;
} else {
if (isOperandChar(c)) {
encounteredOperandStart = true;
currentOperand += c;
}
else if(isParenthesis(c)) {
postfixExpression.add(String.valueOf(c));
//currentOperand = "";
encounteredOperandStart=false;
}
else{
postfixExpression.add(String.valueOf(c));
//currentOperand = "";
encounteredOperandStart=false;
}
}
}
if (!currentOperand.isEmpty()) {
postfixExpression.add(currentOperand);
}
return postfixExpression.toArray(new String[postfixExpression.size()]);
}}
我認為這是您想要的嗎? :)
public static List<String> splitInfixExpression(String someString){
List<String> someList = new ArrayList<String>();
String tempString = "";
for (int i = 0; i < someString.length(); i++){
if (Character.isDigit(someString.charAt(i)) || (someString.charAt(i) == '-' && someString.length() == 0) || someString.charAt(i) == '.'){
tempString += String.valueOf(someString.charAt(i));
tempString = tempString.trim();
}
else{
if (tempString.length() > 0){
someList.add(tempString);
}
tempString = String.valueOf(someString.charAt(i));
if (someList.size() > 0 && Character.isDigit(someList.get(someList.size() - 1).charAt(someList.get(someList.size() - 1).length() - 1))){
someList.add(tempString);
tempString = "";
}
else if (tempString.trim().length() > 0 && ((!tempString.equals("-"))) && ((!tempString.equals("+")))){
someList.add(tempString);
tempString = "";
}
}
}
someList.add(tempString);
return someList;
}
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