Thread: help with calculator program.

I suggest using either Reverse Polish Notation or postfix for your implementation, and using an array as your stack.

Although the recursive types are elegant, I'd recommend the iterative logic for anyone not too familiar with the subject.

Wikipedia has a good write up on RPN and postfix, and there are plenty of other examples you can google, as well.

Post up your code when and if you do get stuck.

Be sure and use [code[ (but reverse the last squared bracket), [/code[ tags around your code, and remember to indent it, OK?

i came back!
Sean, in fact this calculator can get a mathematical term like 3+4*5/sin30 ! according to RPN at first program should put operands and operators in two different stacks

dear Adak I started writing this program, getting the string of numbers and operators and putting each in two arrays as stack, but my program during execution crashes . can any one check it ? Ive used "ispunct" function to recognize my operators.

another question is that how can i omit spaces from array?

Code:

#include <stdio.h>
#include <iostream.h>
#include <ctype.h>
#include <string.h>

#define length 20
int main()
{
	
	char s[length];
	char adad[10];
	char alamat[10];
	int dec;

	cout << "Enter a string" << endl;

	//read in the users data from the input stream and ends by enter

	cin.get(s,'\n');


	//Display a message made up of two strings and the user data
	cout << "ha ha! you entered the string "  << s << endl;

	
	
	/*************initializing arrays************/

	for (int j=0 ; j<length ; j++){
		if (ispunct(s[j])){  
			for (int k=0;k<10;k++)
				adad[k]=s[j];
		}
		else {
			for (int l=0;l<10;l++)
				alamat[l]=s[j];
		}
	}

	/**********preview arrays*************/

	for (int m=0;m<10; m++)
		printf("%c" , adad[m]);
	for (int n=0; n<10; n++)
		printf("%c" , alamat[n]);

	scanf("%d" , dec);
	printf("finally %d" , dec);


	return(0);
}

Not to be picky, but you're using C++, and I have no idea how to work with cin.

May I suggest using

Code:

char Array[50];

fgets(Array, sizeof(Array), stdin);

Then, pick out what you want from the Array, using sscanf() or "walking" through it, and putting ONLY your operators into the stack for operators, and ONLY your numbers into the numbers stack.

So you have no spaces to get rid of (hint: sscanf() will skip spaces when it's looking for some data items).

If you want your program in C++, just say so, and I'll shut up. If it should be a C program, then be sure the program has a c filename extension, and not a cpp extension. Otherwise, you'll be accidentally working with the wrong compiler (C++ instead of C).

You may need to check your compiler and/or workspace options to see what compiler is set to work with what filename extensions. The above is the normal default, but you can set it up to do either:

1) always use C (with any extension), or

2) always use C++ (with any extension), or

3) use C compiler only with filenames that end with c, and C++ for filenames that have the cpp extension.

I recommend initializing your array stacks to '\0', for char's, and 0's for numbers, first.

THEN put in your operators and numbers. You'll see the errors, quite easily.

I think it's much easier also, if you use the common terms pop() and push() (or off and on, if you prefer).

Say you are going through the string, and find an operator - then push() that operator onto the stack. In the push() function, you will

1) first move all the current stack down (up in index number), by one. You'll do that from the highest index number, to the lowest, not the other way around, so no temporary variable is needed.

2) Then you'll push the newest value, into the array[0] position.

pop() will work about the same, but in reverse, you'll call pop() when you need to retrieve the next operator or number.

1) You'll pop off the top (lowest index number) item in the array, and then

2) You'll move all the lower items, (which have a higher index number), up one, decrementing by one.

Think of the spring loaded plate holders in a restaurant. Perfect imagery for a first in, last out, stack.

Originally Posted by sadr

i camed back!
Sean, in fact this calculator can get a mathematical term like 3+4*5/sin30 ! according to RPN at first program shud put operands and operators in two different stacks

dear Adak I started writing this program, getting the string of numbers and operators and putting each in two arrays as stack, but my program during execution crashes . can any one check it ? Ive used "ispunct" function to recognize my operators.

another question is that how can i omit spaces from array?

Code:

#include <stdio.h>
#include <iostream.h>
#include <ctype.h>
#include <string.h>

#define length 20
int main()
{
	
	char s[length];
	char adad[10];
	char alamat[10];
	int dec;

	cout << "Enter a string" << endl;

	//read in the users data from the input stream and ends by enter

	cin.get(s,'\n');


	//Display a message made up of two strings and the user data
	cout << "ha ha! you entered the string "  << s << endl;

	
	
	/*************initializing arrays************/

	for (int j=0 ; j<length ; j++){
		if (ispunct(s[j])){  
			for (int k=0;k<10;k++)
				adad[k]=s[j];
		}
		else {
			for (int l=0;l<10;l++)
				alamat[l]=s[j];
		}
	}

	/**********preview arrays*************/

	for (int m=0;m<10; m++)
		printf("%c" , adad[m]);
	for (int n=0; n<10; n++)
		printf("%c" , alamat[n]);

	scanf("%d" , dec);
	printf("finally %d" , dec);


	return(0);
}

You are mixing C with C++.

I dont know what you're trying to achieve but at first glance your array 's' is of 20 length, but operation is of smaller length, this will create problem coz your j loop is running beyond the size of the operation array, so make it of the same size as 's' i.e declare as:

Code:

char operation[20]={'\0'};

Besides it dont use gets.

yes you are right. I never could understand it by myself!

aha! at last I can get over this step !