Finding palindrome in C - c

Question

A palindrome is a word that reads the same from left to right and from right to left.
I wrote a program that finds palindromes from a console.
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#define SIZE 100
int main() {
int i = 0, c;
int left, right;
char string[SIZE];
while (EOF != (c = getchar()) || (c = getchar()) != '\n') {
if (isspace(c) != 0) {
if (i > 0) {
left = 0;
right = i - 1;
while (right > left) {
if (string[left] != string[right]) {
i = 0;
break;
}
++left;
--right;
}
if (left >= right) {
while (i > 0)
printf("%c", string[--i]);
printf("%c", c);
}
i = 0;
}
if (c == '\n')
break;
}
else {
string[i++] = c;
}
}
}
For example, we enter the words: dad sad mum. She outputs: dad mum. But if we write dad sad or dad mum sad. The output will be: dad mum.
That is, an extra space is printed when the last word we read is not a palindrome. How can you get around this situation?

Answer 1

Code is convoluted
First read input properly and form a string.
for (i = 0; i < SIZE - 1; i++) [
int ch = getchar();
if (ch == EOF || ch == '\n') {
break;
}
string[i++] = (char) ch;
}
string[i] = 0;
Then process the string in string[]. Only print spaces when needed.
const char *separator = "";
int i = 0;
while (string[i]) {
// Beginning of a word?
if (!isspace(string[i])) {
int start = i;
int end = i;
while (!isspace(string[end+1]) && string[end+1]) {
end++;
}
// At this point, start indexes the 1st char of the word
// and end indexes the last char of the word
// Now find if a palindrome
while (start <= end && string[start] == string[end]) {
start++;
end--;
}
// Found a palindrome?
if (start > end) {
fputs(separator, stdout);
separator = " "; // print a space _next_ time
while (!isspace(string[i]) && string[i]) {
fputc(string[i++], stdout);
}
} else {
i = end + 1;
}
} else {
i++;
}
}
fputc('\n', stdout);

Answer 2

Life is easier if you just read the string all at once, then process the string.
char s[1000];
fgets( s, sizeof(s), stdin );
char * p = strchr( s, '\n' );
if (p) *p = '\0';
If you wanted to read one character at a time you should read once, test twice:
int c;
while ( ((c = getchar()) != '\n') and (c != EOF) )
But trying to compute the palindrome-ness at the same time as reading seriously makes your algorithm waaaaay more complicated than it needs to be. Read a string first, then compute.
Now you can use integer indices from each end of the string. If you can get them to meet (or cross) then you’ve got a palindrome. Hint: put that in a function:
bool is_palindrome( const char * s )
{
int left = 0;
int right = strlen(s) - 1;
...
}