using System;
class Program
{
/// <summary>/// Determines whether the string is a palindrome./// </summary>
public static bool IsPalindrome(string value)
{
int min = 0;
int max = value.Length - 1;
while (true)
{
if (min > max)
{
return true;
}
char a = value[min];
char b = value[max];
if (char.ToLower(a) != char.ToLower(b))
{
return false;
}
min++;
max--;
}
}
static void Main()
{
string[] array =
{
"civic",
"deified",
"deleveled",
"devoved",
"dewed",
"Hannah",
"kayak",
"level",
"madam",
"racecar",
"radar",
"redder",
"refer",
"repaper",
"reviver",
"rotator",
"rotor",
"sagas",
"solos",
"sexes",
"stats",
"tenet",
"Dot",
"Net",
"Perls",
"Is",
"Not",
"A",
"Palindrome",
""
};
foreach (string value in array)
{
Console.WriteLine("{0} = {1}", value, IsPalindrome(value));
}
}
}civic = True
deified = True
deleveled = True
devoved = True
dewed = True
Hannah = True
kayak = True
level = True
madam = True
racecar = True
radar = True
redder = True
refer = True
repaper = True
reviver = True
rotator = True
rotor = True
sagas = True
solos = True
sexes = True
stats = True
tenet = True
Dot = False
Net = False
Perls = False
Is = False
Not = False
A = True
Palindrome = False
= True
Sentences. This program is the same as the simpler palindrome method except for some small changes. The important change is inside IsPalindrome. There are two additional while-loops.
using System;
class Program
{
/// <summary>/// Determines whether the string is a palindrome./// </summary>
public static bool IsPalindrome(string value)
{
int min = 0;
int max = value.Length - 1;
while (true)
{
if (min > max)
{
return true;
}
char a = value[min];
char b = value[max];
// Scan forward for a while invalid.
while (!char.IsLetterOrDigit(a))
{
min++;
if (min > max)
{
return true;
}
a = value[min];
}
// Scan backward for b while invalid.
while (!char.IsLetterOrDigit(b))
{
max--;
if (min > max)
{
return true;
}
b = value[max];
}
if (char.ToLower(a) != char.ToLower(b))
{
return false;
}
min++;
max--;
}
}
static void Main()
{
string[] array =
{
"A man, a plan, a canal: Panama.",
"A Toyota. Race fast, safe car. A Toyota.",
"Cigar? Toss it in a can. It is so tragic.",
"Dammit, I'm mad!",
"Delia saw I was ailed.",
"Desserts, I stressed!",
"Draw, O coward!",
"Lepers repel.",
"Live not on evil.",
"Lonely Tylenol.",
"Murder for a jar of red rum.",
"Never odd or even.",
"No lemon, no melon.",
"Senile felines.",
"So many dynamos!",
"Step on no pets.",
"Was it a car or a cat I saw?",
"Dot Net Perls is not a palindrome.",
"Why are you reading this?",
"This article is not useful.",
"...",
"...Test"
};
foreach (string value in array)
{
Console.WriteLine("{0} = {1}", value, IsPalindrome(value));
}
}
}A man, a plan, a canal: Panama. = True
A Toyota. Race fast, safe car. A Toyota. = True
Cigar? Toss it in a can. It is so tragic. = True
Dammit, I'm mad! = True
Delia saw I was ailed. = True
Desserts, I stressed! = True
Draw, O coward! = True
Lepers repel. = True
Live not on evil. = True
Lonely Tylenol. = True
Murder for a jar of red rum. = True
Never odd or even. = True
No lemon, no melon. = True
Senile felines. = True
So many dynamos! = True
Step on no pets. = True
Was it a car or a cat I saw? = True
Dot Net Perls is not a palindrome. = False
Why are you reading this? = False
This article is not useful. = False
... = True
...Test = False
Performance. What is the advantage of using two sub-loops to skip forward and back? This approach means you do not need to allocate any new strings.
And You can check the original string data without converting it. Avoiding string allocations makes a program faster.
Info A slower approach strips all spaces and punctuation from the source string. Then, you could use the simpler palindrome method.
A summary. We introduced a simple C# method that tests for palindromes. Many palindromes are composed of multiple words and have spaces and punctuation. These can all be tested.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Feb 18, 2023 (simplify).
