Answers for "infix to postfix in c program"

infix to postfix program in c++

/*https://github.com/Sudhanshu1304/Stack-Application*/

#include <iostream>
#include<string>
using namespace std;



class Stack{


private:


    char A[5];
    int Size;

public:
    int top;
    Stack(){

        top=-1;
        Size=sizeof(A)/sizeof(char);

    }



    bool IsFull(){

        if(top==Size-1){
            return true;
        }
        else{
            return false;
        }
    }

    bool IsEmpty(){

        if(top==-1){
            return true;
        }
        else{
            return false;
        }
    }

    char peek(){

        return A[top];
    }

    void Push(char val){

        if (IsFull()==false){
            top++;
            A[top]=val;
        }
        else{
            cout<<"nThe Stack is Full"<<endl;
        }
    }

    char Pop(){

        if(IsEmpty()==false){
            char temp=A[top];
            A[top]='0';
            top--;
            return temp;
        }
        else{
            return '-1';
        }

    }

    void Show_Stack(){


        for(int i=0;i<top+1;i++){
            cout<<A[i];
        }


    }

};


int Search(char A){


    string CHAR[]={"([","{)","]}","+-","*/","^$"};
    int Size=(sizeof(CHAR)/sizeof(string));

    for(int i=0;i<Size;i++){

        if(A==CHAR[i][0]){
                if(i+i>=6){
                    return i+i;
                }
                else{
                    return i+i+0;
                }

        }
        else if(CHAR[i][1]==A){
             if(i+i>=6){
                    return i+i;
                }
                else{
                    return i+i+1;
                }
        }
    }
    return -1;

}




void Display(char ch,string vari, Stack &s){

    int Size=s.top+1;


    cout<<"n   "<<ch<<"           ";
    s.Show_Stack();
    for(int i=0;i<10-Size;i++){
        cout<<" ";
    }
    cout<<vari<<endl;

}


int main(){

    Stack STACK;
    char temp;
    string exp;//"A+B*C";
    cout<<"Enter Your Expression :";
    cin>>exp;

    string out="";
    cout<<"nnExpression   Stack   Postfixn"<<endl;
    for(int i=0;i<exp.size();i++){

        temp=exp[i];

        int ab=Search(temp);

        if (ab!=-1){

            /* If We ENCOUNTER CLOSING BRACKETS*/
            if(ab<=5 && ab>=3){



                while(Search(STACK.peek())>2){
                    char val=STACK.Pop();
                        out=out+val;

                    Display(temp,out,STACK);
                }
                STACK.Pop();
                Display(temp,out,STACK);
                }
            /* Search Precedence*/
            else{
                if (Search(temp)>=0 && Search(temp)<=2){
                    STACK.Push(temp);
                    Display(temp,out,STACK);
                }

                /* If TOP < Temp */

                else if(Search(STACK.peek())<ab){

                        STACK.Push(temp);
                        Display(temp,out,STACK);
                }
                else{
                    /* if STACK= +,* and temp= + then we have to remove two times */


                    while(Search(STACK.peek())>=ab){

                        char val=STACK.Pop();
                            out=out+val;
                        Display(temp,out,STACK);
                    }
                    STACK.Push(temp);
                    Display(temp,out,STACK);
                }
            }
        }
        /* If an Alphabet */
        else{

            out=out+temp;
            Display(temp,out,STACK);

            }


    }
    while(STACK.IsEmpty()==false){

        char val=STACK.Pop();

            out=out+val;
        Display(temp,out,STACK);

    }
    cout<<"nnFINAL STRING : "<<out<<endl;


}

infix to postfix conversion c++

//Easiet way to solve infix to postfix expression
bool isOperator(char c)
{
	if(c=='+'||c=='-'||c=='*'||c=='/'||c=='^')
	{
		return true;
	}
	else
	{
		return false;
	}
}

int precedence(char c) 
{ 
    if(c == '^') 
    return 3; 
    else if(c == '*' || c == '/') 
    return 2; 
    else if(c == '+' || c == '-') 
    return 1; 
    else
    return -1; 
} 

string InfixToPostfix(stack<char> s, string infix)
{
	string postfix;
	for(int i=0;i<infix.length();i++)
	{
		if((infix[i] >= 'a' && infix[i] <= 'z')
		||(infix[i] >= 'A' && infix[i] <= 'Z'))
		{
			postfix+=infix[i];
		}
		else if(infix[i] == '(')
		{
			s.push(infix[i]);
		}
		else if(infix[i] == ')')
		{
			while((s.top()!='(') && (!s.empty()))
			{
				char temp=s.top();
				postfix+=temp;
				s.pop();
			}
			if(s.top()=='(')
			{
				s.pop();
			}
		}
		else if(isOperator(infix[i]))
		{
			if(s.empty())
			{
				s.push(infix[i]);
			}
			else
			{
				if(precedence(infix[i])>precedence(s.top()))
				{
					s.push(infix[i]);
				}	
				else if((precedence(infix[i])==precedence(s.top()))&&(infix[i]=='^'))
				{
					s.push(infix[i]);
				}
				else
				{
					while((!s.empty())&&( precedence(infix[i])<=precedence(s.top())))
					{
						postfix+=s.top();
						s.pop();
					}
					s.push(infix[i]);
				}
			}
		}
	}
	while(!s.empty())
	{
		postfix+=s.top();
		s.pop();
	}
	
	return postfix;
}

int main() 
{  

  	string infix_exp, postfix_exp;
  	cout<<"Enter a Infix Expression :"<<endl;
  	cin>>infix_exp;
  	stack <char> stack;
	cout<<"INFIX EXPRESSION: "<<infix_exp<<endl;
  	postfix_exp = InfixToPostfix(stack, infix_exp);
  	cout<<endl<<"POSTFIX EXPRESSION: "<<postfix_exp;
	  
	return 0;
}