Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

Chapter 8 ■ Arrays
The function palindrome is shown in Program P8.4, which tests it by reading several words
and printing whether or not each is a palindrome.
Program P8.4
#include <stdio.h>
#include <string.h>
int main() {
char aWord[100];
int palindrome(char str[]);
printf("Type a word. (To stop, press 'Enter' only): ");
gets(aWord);
while (strcmp(aWord, "") != 0) {
if (palindrome(aWord)) printf("is a palindrome\n");
else printf("is not a palindrome\n");
printf("Type a word. (To stop, press 'Enter' only): ");
gets(aWord);
}
} //end main
int palindrome(char word[]) {
int lo = 0;
int hi = strlen(word) - 1;
while (lo < hi)
if (word[lo++] != word[hi--]) return 0;
return 1;
} //end palindrome
In the function, we use the single statement
if (word[lo++] != word[hi--]) return 0;
to express all the logic of the body of the while loop in the above algorithm. Since we use ++ and
-- as suffixes, lo and hi are changed after word[lo] is compared with word[hi].
We could, of course, have expressed it as:
if (word[lo] != word[hi]) return 0;
lo++;
hi--;
The program prompts the user to type a word and tells her if it is a palindrome. It then
prompts for another word. To stop, the user must press the “Enter” or “Return” key only. When
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