Solved

# postfix calculator  using stacks

Posted on 1998-02-05
1,977 Views
I need to write a program that is a post fix calculator.
The program must be able to deal with the user either entering a floating point number or a '+' ,a '-',a '*' ,or a '/'.  If one or more numbers are entered and the user hits return before entering the operation symbols '*\+-', then the list of numbers must be printed out from the stack.  If a user enters an operation symbol (=-*/) then the operation must be performed on the two numbers previous to it and the result  must be placed on the stack which is then printed out.  If the user hits q then the current stck must be printed out. If the user enters an operation on the stack and only one number has been entered previously, then an error message must be printed.  How can i do this ?  The data is scanned in as a string..but then must be tested against atof...i have read that atofs behavior is undefined if it does not come against a number when called.  I don't know how to implement this all into a loop ? suggestions! please....
0
Question by:lkitchen
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points
• 2

LVL 3

Accepted Solution

q2guo earned 200 total points
ID: 1257182
I assume that you have a structure call stack
and it contains the following member functions

char pop(void);
void push(char x);
bool isEmpty();
----------------------------------------------------
#include <stdio.h>
#include <ctype.h>
main(void)
{
Stack *postFixc = new Stack;
char temp, opt1, opt2;
char str1[2] = {' ', '\0'};
char str2[2] = {' ', '\0'};

do {
temp = getNextChar();
if (temp == '+') {
if(!postFixc->isEmpty()) return 1;
opt1 = postFixc->pop();
if(!postFixc->isEmpty()) {
while(!postFixc->isEmpty())
printf("%c\n", postFixc->pop())
return 0;
}
opt2 = postFixc->pop();
str1[0] = opt1;
str2[0] = opt2;
temp = atoi(str1) + atoi(str2);
printf("%d\n", temp);
postFixc->push(temp);
}
elseif %2
0

LVL 3

Expert Comment

ID: 1257183
Refer any standard book on Data structures and Algorithms. One of the first things that you will find is stacks and post fix notation.
0

Expert Comment

ID: 1257184
See page 75, K&R, "The C Programming Language"
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

### Suggested Solutions

Console based application in Linux 1 105
NEED HELP WITH VISUAL STUDIO 2017 (beginner) 6 101
windows 10 pro lost profile. 10 85
Secondary drive is failing... D Volume 11 96
This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
Examines three attack vectors, specifically, the different types of malware used in malicious attacks, web application attacks, and finally, network based attacks.  Concludes by examining the means of securing and protecting critical systems and inf…
The goal of this video is to provide viewers with basic examples to understand and use for-loops in the C programming language.
The goal of this video is to provide viewers with basic examples to understand opening and reading files in the C programming language.
###### Suggested Courses
Course of the Month6 days, 15 hours left to enroll