C PROGRAMMING PROGRAM • STRINGS
Check Whether a String Is a Palindrome
Learn how to check whether a string is a palindrome using a clear C program.
PROBLEM UNDERSTANDING
Input and expected output
Sample input
level
Sample output
Palindrome
COMPLETE C PROGRAM
Complete C implementation
#include <stdio.h>
#include <string.h>
int main(void)
{
char text[200];
int palindrome = 1;
fgets(text, sizeof text, stdin);
text[strcspn(text, "\n")] = '\0';
int left = 0, right = (int) strlen(text) - 1;
while (left < right) {
if (text[left] != text[right]) { palindrome = 0; break; }
left++; right--;
}
printf(palindrome ? "Palindrome\n" : "Not a palindrome\n");
return 0;
}CURRENT STEP
SELECTED LINE
EXPECTED OUTPUT FOR THE SAMPLE
Palindrome
Step 0 of 0
PROGRAM EXPLANATION
Algorithm and explanation
- Read the required input values.
- Compare characters from both ends and stop when a mismatch is found.
- Display the computed result.
Compare characters from both ends and stop when a mismatch is found.
EFFICIENCY
Time and space complexity
Time complexity
O(n)
Auxiliary space
O(1)
DEBUGGING CHECKLIST
Common mistakes
Check this
Use the correct format specifier for every variable.
Check this
Initialize variables before using their values.
Check this
Check braces, semicolons and input order carefully.
Try it yourself
Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.
