Skip to main content

Checking if String is Palindrome in C Recursively

Palindrome String :  are those string which is same if you read it backwards."MADAM" or "AABBCCCCBBAA" are palindrome strings. But "ABBC" is not


Recursive Method: Why would you use recursive method when you have a really easy non recursive method? Anyways here is a (rather unoptimised) way to do it in C.
we create a function and pass string , first chars index and last chars index to match, then call it recursively if it matches (Pretty clever right ).

Code:
#include<stdio.h>
#include<string.h>//for strlen function
int checkPalindromeStr(char* p, int start, int end)// here start and end are index of strat char and end char to match
{
    if(start>end)
    {
        return(1);
    }
    else if(*(p+start)==*(p+end))
    {
        checkPalindromeStr(p,start+1,end-1);//recursive call for next char to match    
    }
    else
    {
        return(0);
    }
}
void main()
{
    char* s="aabaa";
    int l;
    l=strlen(s);
    if(checkPalindromeStr(s,0,l-1))// we start by matching 0th char with last char
    {
        printf("\n String is Palindrome\n");
    }
    else
    {
        printf("\n String is not Palindrome\n");
    }
}

Popular posts from this blog

Overloading Unary Operator in C++

In this Example I will demonstrate overloading a unary operator. The overloading is done in similar way as we did for binary operator. In this example I will be using a Vector Class. The operator we are going to over load is the unary "~" (tilde) operator. although you can use any unary overloadable operator. Method: In this example the overloaded operator will be the part of the class i.e. the over loaded definition will be a member function. (As we know overloading can be done using non member functions too). So the unary operator will not have any arguments in it. We will overload ~ operator so that it will reflect the vector so that its z component becomes x component and vice versa. So input vector will be 2i+3j+5k and its output vector will be 5i+3j+2k. although you can do anything you like. Code: # include < iostream > using namespace std ; class vector { int x , y , z ;      public : vector ( ) { x = y = z = 0 ; ...

calculating leap year in c using if else

Most new students get really confused when it comes to calculating Leap year in C. It is given as an exercise to enhance their knowledge about using if else usages. This can be calculated using Logical operators too. But using if else provides clearer ways to calculate it. Both of the methods can be implemented in C/C++ program. Here we will discuss the if else method in C/C++