infix to postfix program in c 2b 2b

1/*https://github.com/Sudhanshu1304/Stack-Application*/
2
3#include <iostream>
4#include<string>
5using namespace std;
6
7
8
9class Stack{
10
11
12private:
13
14
15    char A[5];
16    int Size;
17
18public:
19    int top;
20    Stack(){
21
22        top=-1;
23        Size=sizeof(A)/sizeof(char);
24
25    }
26
27
28
29    bool IsFull(){
30
31        if(top==Size-1){
32            return true;
33        }
34        else{
35            return false;
36        }
37    }
38
39    bool IsEmpty(){
40
41        if(top==-1){
42            return true;
43        }
44        else{
45            return false;
46        }
47    }
48
49    char peek(){
50
51        return A[top];
52    }
53
54    void Push(char val){
55
56        if (IsFull()==false){
57            top++;
58            A[top]=val;
59        }
60        else{
61            cout<<"\nThe Stack is Full"<<endl;
62        }
63    }
64
65    char Pop(){
66
67        if(IsEmpty()==false){
68            char temp=A[top];
69            A[top]='0';
70            top--;
71            return temp;
72        }
73        else{
74            return '-1';
75        }
76
77    }
78
79    void Show_Stack(){
80
81
82        for(int i=0;i<top+1;i++){
83            cout<<A[i];
84        }
85
86
87    }
88
89};
90
91
92int Search(char A){
93
94
95    string CHAR[]={"([","{)","]}","+-","*/","^$"};
96    int Size=(sizeof(CHAR)/sizeof(string));
97
98    for(int i=0;i<Size;i++){
99
100        if(A==CHAR[i][0]){
101                if(i+i>=6){
102                    return i+i;
103                }
104                else{
105                    return i+i+0;
106                }
107
108        }
109        else if(CHAR[i][1]==A){
110             if(i+i>=6){
111                    return i+i;
112                }
113                else{
114                    return i+i+1;
115                }
116        }
117    }
118    return -1;
119
120}
121
122
123
124
125void Display(char ch,string vari, Stack &s){
126
127    int Size=s.top+1;
128
129
130    cout<<"\n   "<<ch<<"           ";
131    s.Show_Stack();
132    for(int i=0;i<10-Size;i++){
133        cout<<" ";
134    }
135    cout<<vari<<endl;
136
137}
138
139
140int main(){
141
142    Stack STACK;
143    char temp;
144    string exp;//"A+B*C";
145    cout<<"Enter Your Expression :";
146    cin>>exp;
147
148    string out="";
149    cout<<"\n\nExpression   Stack   Postfix\n"<<endl;
150    for(int i=0;i<exp.size();i++){
151
152        temp=exp[i];
153
154        int ab=Search(temp);
155
156        if (ab!=-1){
157
158            /* If We ENCOUNTER CLOSING BRACKETS*/
159            if(ab<=5 && ab>=3){
160
161
162
163                while(Search(STACK.peek())>2){
164                    char val=STACK.Pop();
165                        out=out+val;
166
167                    Display(temp,out,STACK);
168                }
169                STACK.Pop();
170                Display(temp,out,STACK);
171                }
172            /* Search Precedence*/
173            else{
174                if (Search(temp)>=0 && Search(temp)<=2){
175                    STACK.Push(temp);
176                    Display(temp,out,STACK);
177                }
178
179                /* If TOP < Temp */
180
181                else if(Search(STACK.peek())<ab){
182
183                        STACK.Push(temp);
184                        Display(temp,out,STACK);
185                }
186                else{
187                    /* if STACK= +,* and temp= + then we have to remove two times */
188
189
190                    while(Search(STACK.peek())>=ab){
191
192                        char val=STACK.Pop();
193                            out=out+val;
194                        Display(temp,out,STACK);
195                    }
196                    STACK.Push(temp);
197                    Display(temp,out,STACK);
198                }
199            }
200        }
201        /* If an Alphabet */
202        else{
203
204            out=out+temp;
205            Display(temp,out,STACK);
206
207            }
208
209
210    }
211    while(STACK.IsEmpty()==false){
212
213        char val=STACK.Pop();
214
215            out=out+val;
216        Display(temp,out,STACK);
217
218    }
219    cout<<"\n\nFINAL STRING : "<<out<<endl;
220
221
222}

1//Easiet way to solve infix to postfix expression
2bool isOperator(char c)
3{
4	if(c=='+'||c=='-'||c=='*'||c=='/'||c=='^')
5	{
6		return true;
7	}
8	else
9	{
10		return false;
11	}
12}
13
14int precedence(char c) 
15{ 
16    if(c == '^') 
17    return 3; 
18    else if(c == '*' || c == '/') 
19    return 2; 
20    else if(c == '+' || c == '-') 
21    return 1; 
22    else
23    return -1; 
24} 
25
26string InfixToPostfix(stack<char> s, string infix)
27{
28	string postfix;
29	for(int i=0;i<infix.length();i++)
30	{
31		if((infix[i] >= 'a' && infix[i] <= 'z')
32		||(infix[i] >= 'A' && infix[i] <= 'Z'))
33		{
34			postfix+=infix[i];
35		}
36		else if(infix[i] == '(')
37		{
38			s.push(infix[i]);
39		}
40		else if(infix[i] == ')')
41		{
42			while((s.top()!='(') && (!s.empty()))
43			{
44				char temp=s.top();
45				postfix+=temp;
46				s.pop();
47			}
48			if(s.top()=='(')
49			{
50				s.pop();
51			}
52		}
53		else if(isOperator(infix[i]))
54		{
55			if(s.empty())
56			{
57				s.push(infix[i]);
58			}
59			else
60			{
61				if(precedence(infix[i])>precedence(s.top()))
62				{
63					s.push(infix[i]);
64				}	
65				else if((precedence(infix[i])==precedence(s.top()))&&(infix[i]=='^'))
66				{
67					s.push(infix[i]);
68				}
69				else
70				{
71					while((!s.empty())&&( precedence(infix[i])<=precedence(s.top())))
72					{
73						postfix+=s.top();
74						s.pop();
75					}
76					s.push(infix[i]);
77				}
78			}
79		}
80	}
81	while(!s.empty())
82	{
83		postfix+=s.top();
84		s.pop();
85	}
86	
87	return postfix;
88}
89
90int main() 
91{  
92
93  	string infix_exp, postfix_exp;
94  	cout<<"Enter a Infix Expression :"<<endl;
95  	cin>>infix_exp;
96  	stack <char> stack;
97	cout<<"INFIX EXPRESSION: "<<infix_exp<<endl;
98  	postfix_exp = InfixToPostfix(stack, infix_exp);
99  	cout<<endl<<"POSTFIX EXPRESSION: "<<postfix_exp;
100	  
101	return 0;
102}