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Copy pathinfixPostfix.cpp
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125 lines (117 loc) · 2.51 KB
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#include <iostream>
#include <string.h>
#include <cctype>
#include <stdio.h>
using namespace std;
class post_eval
{
char infix[100];
char stk[100];
int top = 0;
char str[100];
int k = 0;
public:
void create()
{
int l = 0;
cout<<"Infix Expression->";
cin >> infix;
l = strlen(infix);
infix[l] = ')';
infix[l + 1] = '\0';
stk[0] = '(';
}
void process()
{
int i;
i = 0;
while (infix[i] != '\0')
{
if (infix[i] == '(')
{
push_stack(infix[i]);
}
else if (isdigit(infix[i]))
{
add_postfix(infix[i]);
}
else if (isalpha(infix[i]))
{
add_postfix(infix[i]);
}
else if (infix[i] == ')')
{
while (stk[top] != '(')
{
add_postfix(stk[top]);
pop();
}
pop();
}
else if (infix[i] == '*' || infix[i] == '/' || infix[i] == '+' || infix[i] == '-' || infix[i] == '^')
{
if (stk[top] == '('){
push_stack(infix[i]);
}
else if (prece(stk[top]) >= prece(infix[i])){
while (prece(stk[top]) >= prece(infix[i])){
add_postfix(stk[top]);
pop();
}
push_stack(infix[i]);
}
else if (prece(stk[top]) < prece(infix[i])){
push_stack(infix[i]);
}
}
i++;
}
}
void push_stack(char x)
{
top++;
stk[top] = x;
}
void pop()
{
// cout<<"\nElement popped "<<stk[top];
top--;
}
int prece(char op)
{
if (op == '+' || op == '-')
{
return 1;
}
else if (op == '*' || op == '/')
{
return 2;
}
else if (op == '^')
{
return 3;
}
else
{
return 0;
}
}
void add_postfix(char y)
{
str[k] = y;
//cout<<"\nelement came in postfix string"<<str[k];
k++;
str[k] = '\0';
}
void show()
{
cout << "postfix expression-> " << str;
}
};
main()
{
post_eval ob;
ob.create();
ob.process();
ob.show();
}