C# Program to Convert Infix to Postfix

This C# Program Converts Infix to Postfix. Here the infix expression is obtained from the user and is converted to postfix expression which consists of primary expressions or expressions in which postfix operators follow a primary expression.

Here is source code of the C# Program to Convert Infix to Postfix. The C# program is successfully compiled and executed with Microsoft Visual Studio. The program output is also shown below.

```
/*
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 * C# Program to Convert Infix to Postfix

```
 */
```
```
using System;
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```
using System.Collections.Generic;
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```
using System.Linq;
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```
using System.Text;
```
```
namespace Infix
```
```
{
```
```
    class Program
```
```
    {
```

        static bool convert(ref string infix, out string postfix)

```
        {
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```
 
```
```
            int prio = 0;
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            postfix = "";
```

            Stack<Char> s1 = new Stack<char>();

            for (int i = 0; i < infix.Length; i++)

```
            {
```
```
                 char ch = infix[i];
```

                 if (ch == '+' || ch == '-' || ch == '*' || ch == '/')

```
                 {
```
```
                     if (s1.Count <= 0)
```
```
                         s1.Push(ch);
```
```
                    else
```
```
                    {
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                        if (s1.Peek() == '*' || s1.Peek() == '/')

```
                            prio = 1;
```
```
                        else
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```
                            prio = 0;
```
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                        if (prio == 1)
```
```
                        {
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                            if (ch == '+' || ch == '-')

```
                            {
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                               postfix += s1.Pop();

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                               i--;
```
```
                            }
```
```
                            else
```
```
                            { 
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                                postfix += s1.Pop();

```
                                i--;
```
```
                            }
```
```
                        }
```
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                        else
```
```
                        {
```

                            if (ch == '+' || ch == '-')

```
                            {
```

                               postfix += s1.Pop();

                               s1.Push(ch);

```
 
```
```
                            }
```
```
                            else
```

                                s1.Push(ch);

```
                        }
```
```
                    }
```
```
                }
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                else
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```
                {
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```
                    postfix += ch;
```
```
                }
```
```
            }
```
```
            int len = s1.Count;
```

            for (int j = 0; j < len; j++)

```
                postfix += s1.Pop();
```
```
            return true;
```
```
        }
```
```
        static void Main(string[] args)
```
```
        {
```
```
            string infix = "";
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```
            string postfix = "";
```
```
            if (args.Length == 1)
```
```
            {
```
```
                infix = args[0];
```

                convert(ref infix, out postfix);

                System.Console.WriteLine("InFix  :\t" + infix);

                System.Console.WriteLine("PostFix:\t" + postfix);

```
            }
```
```
            else
```
```
            {
```
```
                infix = "a+b*c-d";
```

                convert(ref infix, out postfix);

                System.Console.WriteLine("InFix   :\t" + infix);

                System.Console.WriteLine("PostFix :\t" + postfix);

                System.Console.WriteLine();

```
                infix = "a+b*c-d/e*f";
```

                convert(ref infix, out postfix);

                System.Console.WriteLine("InFix   :\t" + infix);

                System.Console.WriteLine("PostFix :\t" + postfix);

                System.Console.WriteLine();

                infix = "a-b/c*d-e--f/h*i++j-/k";

                convert(ref infix, out postfix);

                System.Console.WriteLine("InFix   :\t" + infix);

                System.Console.WriteLine("PostFix :\t" + postfix);

                System.Console.WriteLine();

```
                Console.ReadLine();
```
```
            }
```
```
        }
```
```
    }
```
```
}
```

Here is the output of the C# Program:

Infix   : a+b*c-d
Postfix : abc*+d-
 
Infix   : a+b*c-d/e*f
Postfix : abc*+de/f*-
 
Infix   : a-b/c*d-e--f/h*I++j-/k
Postfix : abc/d*-e--fh/I*-=j=k/-

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