Lab46 Wiki

• This is a palindrome program that will take one word entered at the command line and test to see if it is a palindrome.
• This program was above and beyond anything I “needed” to do but I wanted to have it in my portfolio. It covers a lot of attributes. Command line arguments, stacks, pointers, selection etc.

#include<stdio.h>
#include<stdlib.h>
#include"stack.h"
 
 
int main(int argc, char *argv[])// I chose to allow for command line interface
{
	if(argc != 2)// when compiling you will get a warning that 0 or 2 argument is all that is allowed but 
	{            //this is just to make sure user enters one and only one word to test
		printf("Please enter only one word to check at a time\n");
		exit (1);
	}
 
	Stack *myStack, *myStackBackup, *kcatSmy;// myStack is original word, Backup is needed to created kcatSmy which is mystack values backwards
	Node *tmp, *tmp2;// Temps are needed for the various times the pop function is called.
	myStack = (Stack *)malloc(sizeof(Stack));
	myStackBackup = (Stack *)malloc(sizeof(Stack)); 
	kcatSmy = (Stack *)malloc(sizeof(Stack));
	myStack->start = myStack->end = myStackBackup->start = myStackBackup->end = kcatSmy->start = kcatSmy->end = tmp = tmp2 = NULL;
	int i = 0;
 
	printf("Before: ");
	while (argv[1][i] != '\0') // this tests for the end of the string the user entered
	{
		push(myStack, (int)argv[1][i]);
		push(myStackBackup, (int)argv[1][i]); // these lines copy the string from argv into myStack and prints the values
		printf("%c", myStack->end->value);
		i++;
	}
 
	printf("\nAfter: ");
	tmp = pop(myStackBackup); //This pops the value off of myStackBackup and stores the value in the tmp node
	while(tmp!= NULL)// this test lets us know if the stack is been popped until empty
	{
		push(kcatSmy, tmp->value); //this copies each popped value from myStackBackup into kcatSmy
		printf("%c", kcatSmy->end->value);//this prints the values backwards.
		tmp = pop(myStackBackup);// and now we pop again, this is done until the stack is empty
	}
	printf("\n");
	// So now we have to stacks, myStack and kcatSmy, now we need to compare and see if they are the same
	tmp = pop(myStack);// we will pop both stacks
	tmp2 = pop(kcatSmy);
	while(tmp != NULL)// since at this point we know both stacks are the same size you can test either tmp for NULL 
	{
		if (tmp->value != tmp2->value)// as soon as any compared nodeds are not equal we know its not a palindrome so we can exit.
		{
			printf("This is not a palindrome.\n");
			exit (0);
		}
		else
		{
			tmp = pop(myStack);// if the compared nodes are equal we need to move through the list and check each one
			tmp2 = pop(kcatSmy);
		}
	}
		printf("This IS a palindrome!\n");// if we make it through the list and all nodes are equal then we know its a palindrome!
 
	return (0);
}