endswith.c

/*******************************************************************************
*
* Program: Check If A String Ends With Another Stirng
* 
* Description: Example of checking if a string ends with another string in C.
*
* YouTube Lesson: https://www.youtube.com/watch?v=N71-P0i4qPY
*
* Author: Kevin Browne @ https://portfoliocourses.com
*
*******************************************************************************/
#include <stdio.h>
#include <string.h>
#include <stdbool.h>

bool endswith(char *string, char *end);

int main()
{
  // test string
  char mystring[] = "Roses are red";
  
  // check if the test string ends with "red"
  char end_ok[] = "red";
  if (endswith(mystring,end_ok))
    printf("Yes string ends with red.\n");
  else
    printf("No string does not end with red.\n");
  
  // check if the test string ends with "blue"
  char end_not_ok[] = "blue";
  if (endswith(mystring,end_not_ok))
    printf("Yes string ends with blue.\n");
  else
    printf("No string does not end with blue.\n");
  
  // test the error handling code of an "end string" that is longer than the 
  // actual string itself... this length issue *must* result in false
  char too_long[] = "Roses are red violets are blue";
  if (endswith(mystring,too_long))
    printf("Failed to detect issue!\n");
  else
    printf("Length issue detected!\n");
  
  
  return 0;
}

// returns true if the string ends with the string end, and false otherwise
bool endswith(char *string, char *end)
{
  // get the lengths of both strings
  int string_length = strlen(string);
  int end_length = strlen(end);
  
  // if the end string is longer than the string itself, return false as it is
  // not possible for the string to end with the end string
  if (end_length > string_length) return false;
  
  // check the characters at the end of string to see if any of them do no match
  // the characters in the end string, if any do no not, the string does not 
  // end with the end string, and we can return false
  for (int i = 0; i < end_length; i++)
    if (string[string_length - i] != end[end_length - i])
      return false;

  // if we did not find any non-matching characters, the string must end with
  // the end string, and we can return true
  return true;
}