Question

Write a program (InfixToPostfix function) to convert an infix expression that includes +,-, * and / to postfix. int main(int argc, const char argv[l) cout <"Final Result : "<< InfixToPostfix("(5+3)*4" return The above main function should display the result below: Final Result 53+4* Here are some uiliy functions that you may find usefal int precedence(char ch) switch (ch) case case- return 1; case case ソ': return 2 '^': return 3; case

Answer 1

//  Program to convert infix expression into postfix expression

#include<iostream>
#include<cstring>        // For strlen() and strcat()
#include<cctype>         // For isalnum()
#define MAX 50

char stack[MAX];
int top = -1;

// Function to push into the stack
int PUSH(char val)
{
    stack[++top] = val;
}

// Function to pop from the stack
char POP()
{
    return stack[top--];
}

// Function to get priority of an operator
int getPriority(char op)
{
    if(op == '(')
        return 0;
    if(op == '+' || op == '-')
        return 1;
    if(op == '/' || op == '*')
        return 2;
}

// Function to convert infix into postfix
char *infixToPostfix(char infix[])
{
    static char postfix[40];// Declare postfix as static otherwise after returning, postfix will get destroyed!
    int j = 0;
    for(int i = 0; i < strlen(infix); i++)
    {
        if(isalnum(infix[i]))
            postfix[j++] = infix[i];
        else
        if(infix[i] == '(')
            PUSH(infix[i]);
        else
        if(infix[i] == ')' )
        {
            while(stack[top] != '(')
                postfix[j++] = POP();
            POP();
        }
        else
        {
            while(getPriority(infix[i]) <= getPriority(stack[top]))
                postfix[j++] = POP();
            PUSH(infix[i]);
        }
    }
    while(top != -1)
        postfix[j++] = POP();
    return postfix;
}

int main()
{
    std::cout<<"Final Result: "<<infixToPostfix("(5+3)*4");
    return 0;
}

OUTPUT:

$CAUsers Shubham\Desktop InfixToPostfix.exe Final Result 53+4* Process exited after 0.02284 seconds with return value e Press any key to continue . .$