Counting Words in a String using C

Counting words in a String using C:
This is very good exercise to test new programmers pointer skills. The task is to count the words in a given string using C. Well there might be many ways you can do it, I will demonstrate mine way.
Note that mine solution might not be the optimal one, but it gets the job done.

Operator Overloading using Friend Functions with Complex Numbers

Operator overloading using friend functions:


Operators can be overloaded in c++ with friend functions also. The procedure is same as we discussed earlier. Here I will demonstrate operator overloading with "+" operator which is a binary operator. I will be using a complex number class (called complex). The class will have 2 data types, real and imaginary.
Operator overloading will not be a part of class complex, but we will declare that this function is a friend of class complex.

Find nth Prime Number in C++

c++ program to find prime numbers:


The problem of finding prime number can be solved by checking all numbers, testing them for prime and then moving ahead. If you want to calculate nth prime. Then this can be done in a brutal way by checking the number one by one. This may sound odd, by there is no easy way then this  for prime numbers (Well Actually there are like Pollard's Rho Algorithm, Number Sieves or Shor's Quantum Algorithm, but we are talking about the one that most people may understand easily). There may be way to pre-calculate the prime numbers but that again is not sufficient. So how can we use c++ to create a program to find prime numbers.

Program for Multi Level Inheritance and Function Overriding

Program for Multi Level Inheritance and Function Overriding:
Function overriding is a very key programming feature in OOP system. This allows programmers to create objects which has similar function ( with same name) but having different implementations. Such technique is really helpful in situations where each object has a common function but implementations ( games for example).

News: All Code now have color highlighting

I have updated my codes to now have color highlighting, This will make code look a little better :)
Cheers

Program for Matrix Multiplication in C++ using Operator Overloading

Program for Matrix Multiplication in C++ using Operator Overloading :
We will now try to multiply two matrix by using the concept of operator overloading. The described way is very very easy to understand. We will be overloading "*" operator for this purpose. Although this can be done by any binary operator.

Stack in C using functions

Stack in C: Stack is a very useful data structure in C, It is used in many situations. Implementing stack can be done using a global array and a global pointer of the stack. although this implementation reveals how good OOP is for such situations. There will be three basic functions of the stack. One will be push() operation, which will push the given element to the stack. Pop() function  will pop out the element from the top. A show function to show the content of the stack.

Pointers in C for starters

Ask any new computer science student ,"What is the most dreaded topic in C language?". They will reply ,"Still having nightmares about pointers !!!". And I don't blame them. In fact pointers become even more dreaded as the learning curve is really steep for beginner.

So what makes pointers so "evil" ? I personally think its not the pointers but its lack of knowledge about memory that actually kills a new student. Hence I claim "Pointers are innocent ".

Understanding Constructors in C++

What are Contructors in C++?
Ans: Constructor are special function that can help initialize an object.
Do we really need contructors in C++?
Well, Its a good feature and really helps programmer.
I am a good programmer and I don't Need contructors.
LOL !!!!!
Ok enough of chit chat, lets get to the point. Why contructors were included in C++. The answer lies in very nature of programmers. Programmer frequently get messy with code and allow mistakes to happen ( LOL :P). How? Lets have a look on following code :

#include<iostream>

using namespace std;

int main()

{

int k;

cout<<k;

}

This is a classical example of programmer forgetting to initialize the variable. Hence causing unexpected errors. This problem gets more complicated as we start creating objects. Since objects may have many data, its a very common mistake to forget to initialize the data portions of objects. This is where construcors come handy. The contructors have a property that they get called automatically when objects gets created.

#include<iostream>

using namespace std;

class Me

{

     int x,y;

    public:

   Me()

   {

      x=y=0;

   }

   void show()

   {

       cout<<x<<","y;

   }

};

int main()

{

  Me x;

x.show();

}

Declaring a Constructors will ensure that whatever initialization are put into the contructors to execute always whenever object gets created. Hence objects data will always will be in initialize state.
How to declare Contructors in C++?
Its really easy, just follow the following rules :

• Contructors are public.
• Constructors don't have any return type.
• Constructors name is always as that of the Class.
• Constructors with no arguments are called default constructors.
• Constructors can be overloaded.

So next time you put some initialization code in a contructors, your object won't have garbage values in them.
Happy coding.

Calculate Factorial in python

Objective : Using python calculate factorial of a number.

Logic : the logic is exactly the same as we do it in C language. so we use loops.

Code:

def factorial(number):

    ans=1;

    for i in range(2,number+1):

        ans=ans*i;

    print(ans)

    return

What are the benefits of this code in python over the same in C? well on the first you won't see much advantages, but that's where you overlook Python !!! Python utilizes a heavy bit integers (128 bit integers), so 200! can be easily calculated without using decimal representation. Isn't that cool !!!

Program to check if a number is palindrome or not in C

Objective : To check if given number is palindrome or not in C.

Programming logic : This is a very easy program if you know how to reverse a number. Once you have found the reverse of number just compare it with original, if both are same then the number is palindrome.

Code:

#include<stdio.h>
int main()
{
    int k;
    printf("\n enter number =");
    scanf("%d",&k);
    if(palindrome(k))
    {
        printf("\n The number is palindrome");
    }
    else
    {
        printf("\n The number is not palindrome");
    }
    return(0);
}
int palindrome(int x)
{
    int rev=0;//to calculate reverse of number
    int k=x;
    while(k>0)
    {
        rev=rev*10+k%10;
        k=k/10;
    }
    if(x==rev)// check if reverse is equal to given number
    {
        return(1);//if yes then return 1
    }
    else
    {
        return(0);//else return 0
    }
}

Fibonacci series in C non recursive

Objective : To print given numbers of Fibonacci series. (1,1,2,3,5.....) non recursively.
Programming Logic: Its easy to print the above Fibonacci series in C. the number is always sum of previous 2 terms. This series starts with numbers 1,1. so next term is 1+1=2. Then next term is 1+2=3 and so on.
(It may be noted that series 1,3,4,7,11,18.... is also a Fibonacci series, but it starts with 1,3 )

Code :

#include<stdio.h>
int main()
{
    int k;
    printf("\n enter number of terms to print=");
    scanf("%d",&k);
    fic(k);
    return(0);
}
void fic(int x)// x are number of terms to print
{
    int a,b,sum,i;
    a=b=1;
    printf("1,1,",sum);//first 2  terms
    for(i=0;i<x-2;i++)
    {
        sum=a+b;
        printf("%d,",sum);
        a=b;
        b=sum;    
    }
}

It may be noted that using a non recursive way to calculate Fibonacci series in C provides faster calculations as compared with recursive method. As recursive program have a large overhead of function calls. Also the recursive way is very unoptimised since it doesn't uses the last 2 values that have been calculated already..

Reversing a Number in C

Objective : You are given a  number and you have to find the reverse of the given number in C. reverse of 1234 will be 4321.

Programming logic: The logic lies in constructing the reverse numbers from the digits of the given number. So we extract each digit with % modulus operator and then build the number up.To build the number we simply multiply the reverse number by 10 and then add the next remainder to it.
Like 1234:
1234%10=4 (remainder). rev=4.
123%10= 3. rev=4x10+3=43.
12%10=2 rev=43x10+2=432.
1%10=1 rev=432x10+1=4321.


Code:

#include<stdio.h>
int main()
{
    int k;
   printf("\n enter a number=");
   scanf("%d",&k);
   printf("\n Reverse of the number is=%d",reverse(k));
   return 0;
}
int reverse(int x)
{
    int ans=0,r;
    while( x > 0 )
    {
        r=x%10;//extract last digit
        ans=ans*10+r;// multiply by 10 and then add the remainder
          x=x/10;//reduce number
    }
   return(ans);

}

Integer to Binary in c

Objective : To convert the given integer to binary in C language.

Programming technique : The conversion of integer to binary can be done in many ways. I will demonstrate a very simple (possibly very unoptimised ) way which it is easy to understand.
This way involves using an array to store the remainder of the number when we divide it by 2. The remainder will be saved in array. We will start filling the array from the last and at last we will print the array.
This technique will convert integer number to binary using array, it may not be a true solution but you will get the picture.
we will use % modules operator to extract remainder. Then will reduce the number till it reaches 0. The array will be initialized to 0.

Code :

#include<stdio.h>
int main()
{
    int p;
    printf("\n Enter a number=");
    scanf("%d",&p);
    bin(p);
}

void bin(int x)
{
    long b=0;
    int binary[20],i;
    for(i=0;i<20;i++)
    {
        binary[i]=0;//setting array to 0
    }
    i=19;// starting from last of array
    while(x>0)
    {

        binary[i]=x%2;//save remainder to array
        x=x/2; //reduce number
        i--;//moving index 
    }
    printf("\n Printing Binary=");
    for(i=0;i<20;i++)
    {
        printf("%d",binary[i]);
    }
}

one possible drawback of this technique is that you cant use the binary number directly  in calculations.
Note : The above method will store only 20 digits of binary.

Find Sum of Digits of a Number in C

Objective: Your are given a number and you have to find the sum of its digits. Like 1234 so its digits sum 1+2+3+4=10.

Programming technique : This problem  can be solved using the fact that modulus operator (%) gives the last digit when divided by 10. So we successively Divide it , till all numbers are exhausted.
so The program runs like this >>
1234%10 gives last digit. that is 4. (we save it ) then divide the number by 10 to reduce it.
1234/10=123. and repeat the process till the number becomes 0.
First run : 1234%10 gives 4, 1234/10=123.
Second run: 123%10 gives 3 , 123/10=12.
Third Run :12%10 gives 2 , 12/10=1
Fourth run: 1%10 gives 1, 1/10=0 (we stop here).
pretty easy stuff.

Code :-
#include<stdio.h>

int main()
{
    int k;
    printf("\n enter any number=");
    scanf("%d",&k);
    printf("\n sum of digit=%d",sumdigit(k));
          return(0);
}

int sumdigit(int x)
{
    int sum=0;// will save sum
    int r=0; // for remainder
    while(x>0)
    {
        r=x%10;//get remainder
        sum+=r;//sum it
        x=x/10;    //reduce number
    }
    return(sum);
}

Program to find nth Prime number in C

Objective: To print any Prime number in C. 

This task may sound easy but is a very good exercise to help optimize CPU intensive programs. Finding Prime number is a very CPU hogging task and it becomes even more dreaded as the number starts to grow. Lets say we want to find 30001th prime. how will we find it?? Here is the program.

Programming logic: The easiest method is to check if the given number N is divisible by any number from 2 to N-1.
But it may be noted that we don't need to go beyond the number that is square root of N.  why??
lets have a look.
Say we are testing number 49 for prime number. Our objective is to find any number that may divide it. so we start from 2,3,4 etc. As soon as we cross 7 there will be no number that will divide 49, if there was we have got it earlier since it will be smaller then 7.  Get it?
another example 64 :
2x32
4x16
8x8
16x4
32x2
as you can see when we pass number 8 we don't need to test as the number that will come , we have tested them already. (clever right ?)

Code:

#include <stdio.h>
int main()
{
int count=0;
long a = 2;
while(count<30001)
{
    long b = 2;
    int prime = 1;// to check if found a prime
    while(b * b <= a)
    {
        if(a % b == 0)
        {
            prime = 0;
            break;
        }
        b++;
    }
    if(prime)
    count++;
    a++;
}
printf("%d st prime no. : %ld\n",count,--a);
return 0;
}

It may be noted that this program can be further optimized in several ways. One possible way is to consider only odd terms ( since even terms cant be prime, except 2)

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++

Tools for C/C++ development

C/C++ development can be done in variety of ways. If you are comfortable using the compiler and command prompt, you can just download the compiler and start working. But most of developer will prefer some sort of Integrated development environment (IDE) for C/C++ development.

Calculating Factorial Using Recursion in C

Factorial: its a mathematical function defined as 4!=4x3x2x1=120. Yes just like that. It will multiply all numbers before the given numbers till 1(Worst definition ever).

Calculating Factorial Using For Loop in C

Factorial: its a mathematical function defined as 4!=4x3x2x1=120. Yes just like that. It will multiply all numbers before the given numbers till 1(Worst definition ever).

Calculating LCM of two Numbers in C

LCM : least common multiplier, is a number to which given two numbers can divide exactly (and of course there are a lot of numbers like that , but LCM is the least one of them). E.g. given two numbers 12,15 these numbers can divide 60,120,180 but LCM is 60 as its the least.

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

Checking if String is Palindrome in C

Palindrome String : are those string which is same if you read it backwards."MADAM" or "AABBCCCCBBAA" are palindrome but "TATA" is not. Its a good practice for starters to check their recursion knowledge with this kind of problem. As we know this can be implemented in recursive way too. but a non recursive way will always compare the first letter of the string to the last letter.
Method : checking if string is palindrome in C can be done by creating a function. The Function checkPalindromeStr uses 2 char pointers start and end . Assign first pointer to start char and other to last char. Then we start matching start pointer to end pointer, when they don't match the given string cant be palindrome so we return 0. else we continue by increasing start and decreasing end  till start crosses end pointer. At that point the string will be palindrome and we return 1.

Code:

#include<stdio.h>
#include<string.h>//for strlen function
int checkPalindromeStr(char* p)
{
    int l;
    char* start;//to denote starting char of string
    char* end;// to denote end of string
    l=strlen(p);    //get length of string;
    start=p;//set start to first char of string
    end=p+l-1;//move end pointer to end char of string
    while(start<=end)
    {
        if(*start==*end)
        {
            start++;
            end--;
        }
        else
        {
            return(0);//string is not palindrome
        }
    }
    return(1);
}
void main()
{
    char* s="aabaa";
    if(checkPalindromeStr(s))
    {
        printf("\n String is Palindrome\n");
    }
    else
    {
        printf("\n String is not Palindrome\n");
    }
}

the same problem can be done using recursion.Follow my this post.
http://programs-in-c-plus-plus.blogspot.com/2011/04/checking-if-string-is-palindrome-in-c_22.html

HCF/GCD in C using recursion

HCF: Highest common factor can be calculated using recursive method. HCF is also called as GCD (greatest commomn divisor).

Calculating HCF/GCD of two Numbers in C non recursive

HCF: Highest common factor can be calculated using long division method. HCF is also called as GCD (greatest commomn divisor).
Method: Two numbers x and y and passed to the function HCF which calculates HCF and returns it.
we keep on diviing x with y untill it completely divides x. If it does y becomes HCF, if not then we replace x with the remainder and y with x.
Code:

#include<stdio.h>
int HCF(int x, int y)
{
    int tmp;
    if(x<y)
    {
        tmp=x;
        x=y;
        y=tmp;//using tmp to swap x and y    
    }    
    while(x%y!=0)
    {
        tmp=x%y; //using tmp to store remainder
        y=x;
        x=tmp;    
    }
    return(y);
}
int main()
{
    int k;
    k=HCF(18,24);    
    printf("\n HCF=%d",k);
}