我正在尝试将中缀表达式转换为后缀表达式的代码。目前,如果我输入例如“5 + 6”,程序将正常工作,它将输出正确的答案,即“5 6 +”。当我输入多于一个运算符(例如“5 + 6-3”)时,会出现问题,输出错误答案“+ 3-”。有人可以指出我犯的错误吗?提前致谢 !中缀到Postfix转换
void main(){
Stack *s = new Stack;
string input;
cout <<"Enter Expression"<<endl;
cin>>input;
InfixToPostfix(input);
system("PAUSE");
}
string InfixToPostfix(string input){
Stack *S = new Stack();
string postfix = "";
for (int i=0; i < input.length();i++){
if (input[i]== ' '||input[i]==',') continue;
else if (IsOperator(input[i]))
{
while(!S->IsStackEmpty() && S->StackTop() != '(' && HasHigherPrecedence(S->StackTop(),input[i]))
{
postfix=S->StackTop();
S->Pop();
}
S->Push(input[i]);
}
else if(IsOperand(input[i]))
{
postfix +=input[i];
}
else if (input[i] == '(')
{
S->Push(input[i]);
}
else if (input[i]==')')
{
while(!S->IsStackEmpty() && S->StackTop() != '('){
postfix += S->StackTop();
S->Pop();
}
S->Pop();
}
}
while(!S->IsStackEmpty()){
postfix +=S->StackTop();
S->Pop();
}
cout <<""<<postfix;
return postfix;
}
bool IsOperand(char C)
{
if(C>= '0' && C<= '9') return true;
if(C>= 'a' && C<= 'z') return true;
if(C>= 'A' && C<= 'Z') return true;
return false;
}
bool IsOperator(char C)
{
if(C=='+' || C== '-' || C =='*' || C == '/' ||C == '$')
{
return true;
}else{
return false;
}
}
int IsRightAssociative(char op)
{
if(op=='$'){
return true;
}else{
return false;
}
}
int GetOperatorWeight(char op){
int weight = -1;
switch(op)
{
case'+':
case '-':
weight=1;
break;
case '*':
case '/':
weight=2;
break;
case '$':
weight=3;
break;
}
return weight;
}
int HasHigherPrecedence (char op1, char op2)
{
int op1Weight= GetOperatorWeight(op1);
int op2Weight = GetOperatorWeight(op2);
if(op1Weight == op2Weight)
{
if(IsRightAssociative(op1))
{
return false;
}else{
return true;
}
return op1Weight > op2Weight ? true:false;
}
}
这看起来不像C++/CLI。它看起来像普通的C++和一个未知的Stack类... – Medinoc