Check palindrome and debug - c

Question

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#define FALSE 0
#define TRUE 1
int alphabetic(char *string )
{
int i, valid;
valid = TRUE;
for ( i = 0; i < strlen(string); i++ )
{
if ( toupper ( string[i] ) < 'A' || toupper (string[i] ) > 'Z' )
valid = FALSE;
}
return valid;
}
int main()
{
char c, inputarray[10], temp[10];
int i = 0;
strcpy(temp, inputarray);
printf("%s Please enter string>");
while ( ( c = getchar () ) != '\n')
{
if ( i < 9 )
inputarray[i] = c;
i++;
}
if ( i < 10 )
inputarray[i] = '\0';
else
{
inputarray[9] = '\0';
printf("String too long\n");
return;
}
printf("%s\n",inputarray);
if (! alphabetic (inputarray) )
{
printf("Invalid input");
}
if (strcmp(strrev(inputarray),temp) == 0 )
printf("Palindrome\n");
else
printf("Not palindrome\n");
}
Trying this and still getting 'not palindrome' when input is a palindrome. It says 'stack around inputarray corrupted' when I run the program. Any ideas on how to fix it so reads palindrome and stop the input array being corrupted.

Answer 1

Here is one possible implementation. I've tried to explain in comments as much as I can but feel free toleave a comment if there is something that's not clear.
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdbool.h>
int alphabetic(char *string)
{
int i, valid;
valid = true;
for (i = 0; i < strlen(string); i++)
{
if (toupper(string[i]) < 'A' || toupper(string[i]) > 'Z')
{
valid = false;
// break here we are done;
break;
}
}
return valid;
}
void printArray(char* str)
{
printf("Array = ");
for (int i = 0; i < strlen(str); ++i)
{
printf("%c", str[i]);
}
printf("\n");
}
bool isPalindrome(char* str1, char* str2)
{
bool isValidPalindrome = true;
int length = strlen(str1);
if (length != strlen(str2))
{
printf("Strings must be the same lenth");
isValidPalindrome = false;
}
else
{
--length;
for (int i = length; i >= 0; --i)
{
if (str1[i] != str2[length - i])
{
isValidPalindrome = false;
break;
}
}
}
return isPalindrome;
}
int main()
{
const int length = 10;
char c, inputarray[length], temp[length];
int i = 0;
// Comparing strings that have not been initialized
// produces undefined behavior. Imagine inputArray is equal to:
// inputArray: "my String ... some other unknown stuff"... where does
// the string ends? there is no '\n' in the horizon.
// The stack error you are getting is produced by the statement
// below. I've pusehd this statement below right after inputArray
// has been initialized
// strcpy(temp, inputarray);
// You don't need the format specifier %s unless you
// rewrite your printf statement as printf("%s", "Please enter string");
// for simplicity you can write it as follows
printf("Please enter string: ");
while ((c = getchar()) != '\n')
{
if (i < length - 1)
inputarray[i] = c;
i++;
}
// Pulled the code inside the if to avoid multiple returns // just preference... not needed
if (i < length)
{
inputarray[i] = '\0';
// helper function to print array
printArray(inputarray);
if (!alphabetic(inputarray))
{
printf("Invalid input");
}
// copy the strings here
strcpy(temp, inputarray);
// reverse the string here
strrev(inputarray);
// you will have to roll out your own isPalindrome
// implementation since reversing a string and comparing it
// with itself will always return false e.g.
// inputArray = "hello";
// copy inputArray into temp
// temp = "hello";
// reverse inputArray
// compare strings: "olleh" == "hello" -> false
if (isPalindrome(inputarray, temp) == true)
printf("Palindrome\n");
else
printf("Not palindrome\n");
}
else
{
inputarray[9] = '\0';
printf("String too long\n");
}
return 0;
}

Answer 2

Trying this and still getting 'not palindrome' when input is a palindrome. It says 'stack around inputarray corrupted' when I run the program.
The probable reason for both is that strcpy(temp, inputarray) is called before inputarray is entered. Move this immediately before the if (strcmp(strrev(inputarray),temp) == 0 ), and your program may work. Another error is the %s in printf("%s Please enter string>").