Trying to create a program to check palindromes and semordinlap - c

Question

I'm trying to create a program to check if a given string is a palindrome or an emordinlap (or reverse pair), however when running my program it's outputting that a string is a palindrome but not a reverse pair (such as racecar should be both).
I've been debugging and starring at this compute screen for 3 hours, and I have no idea what's going on. My first instinct was that it's coming from the checkPali function, so I assigned it to pointers, no luck, same issue.
My second guess was to put printf statements everywhere (I cleaned them up), no luck there either.
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
static void *helpPage(void)
{
puts("usage: epi -h -t -s [string] [file]\n");
puts("-h Print this help and exit\n");
puts("-t Run the test strings.\n");
puts("-s Input a string to check if it is either a palindrome or");
puts(" a emordinlap, followed by the path to a file.");;
}
static char *reverse(char *str)
{
// reverse a given string
char tmp, *src, *dst;
size_t len;
if (str != NULL)
{
len = strlen(str);
if (len > 1)
{
src = str;
dst = src + len - 1;
while (src < dst)
{
tmp = *src;
*src++ = *dst;
*dst-- = tmp;
}
}
}
return str;
}
static char *strip(char *s)
{
// strip a string of a new line
return strtok(s, "\n");
}
static bool checkEpi(char *reversed, char *filePath)
{
// check if the word matches in a given file
// or if the word is an emordnilap
FILE *wordList;
char *line = NULL;
size_t len = 0;
ssize_t read;
wordList = fopen(filePath, "r");
if (wordList == NULL)
{
perror("Failed to open file: "); // file probably doesn't exit
}
while ((read = getline(&line, &len, wordList)) != -1) // read the file line by line
{
if (strip(line) == reversed)
{
return true; // return true if the word matches
}
}
fclose(wordList);
}
static bool checkPali(char *origin, char *reversed)
{
// check if a given word is a palindrome or not
if (*origin == *reversed)
return true;
}
static void checkAll(char *origin, char* reverse, char *filePath)
{
// basically a main function to check if it's a palindrome or a emordnilap
bool paliRes = checkPali(origin, reverse);
bool epiRes = checkEpi(reverse, filePath);
if (paliRes == true)
{
printf("\n%s is a palindrome, it is the same forward and backwards\n", origin);
}
else
{
printf("\n%s is not a palindrome, it is not the same forward and backwards\n", origin);
}
if (epiRes == true)
{
printf("Reverse of %s is a emordinlap, it spells a word backwards.\n\n", origin);
}
else
{
printf("Reverse of %s is not a emordinlap, it does not spell a word backwards\n\n", origin);
}
}
int main(int argc, char *argv[])
{
if (argv[1] == NULL)
{
puts("\nYou failed to pass a valid flag...\n");
helpPage();
return 1;
}
else
{
char *testStrings[] = {"a", "ab", "abc", "another", "cbc", "|0|", "palindrome"};
int i;
char s[10000];
char *defaultWordList = "/usr/share/dict/american-english";
size_t optInt;
for (optInt = 1; optInt < argc && argv[optInt][0] == '-'; optInt++)
{
switch(argv[optInt][1])
{
case 't':
{
for (i = 0; i < sizeof(testStrings) / sizeof(testStrings[0]); i++)
{
strcpy(s, testStrings[i]);
char *origin = testStrings[i];
char *revStr = reverse(s);
checkAll(origin, revStr, defaultWordList);
}
return 0;
}
case 's':
{
if (argv[2] == NULL)
{
puts("\nYou must provide a string to test.\n");
helpPage();
return 1;
}
else if (argv[3] == NULL)
{
puts("\nYou must pass a valid file path to use as a wordlist.\n");
helpPage();
return 1;
}
else
{
//strcpy(s, argv[2]);
char *origin = argv[2];
char *revStr = reverse(argv[2]);
checkAll(origin, revStr, argv[3]);
return 0;
}
}
case 'h': helpPage(); return 0;
}
}
return 0;
}
}
What am I doing wrong to where my statements are not comparing correctly?

Answer 1

You can't meaningfully compare strings using == in C.
if (*origin == *reversed)
This just compares the first char of each of the two parameters. Try strcmp instead.
static bool checkPali(char *origin, char *reversed)
{
/* match if result of strcmp is 0 */
return strcmp(origin, reversed) == 0;
}
You will need a similar change for
if (strip(line) == reversed)