Programs in C & C++ with Example

There seems to be a confusion among people (even authors of Many books) about ways of passing values to a function. Question: How many ways are there to pass a variable to a function in C ? Ans: proposed by most people (authors) : Passing variables by values Passing variables by references My Reaction : Wrong !!!!!!! To make thing even worse, the example most writer put up for passing values by references is this :   #include<stdio.> void swap (int *x, int *y) { int* t; *t=*x; *x=*y; *y=*t; } int main () { int x,y; x=100; y=200; swap(&x,&y); printf("%d,%d",x,y); } I don't know if you get this example or not, But this example is wrong. This example is using pointers , and pointers are not references. So again: Question: How many ways are actually there to pass variables to functions in C ? Well there is only one way: Passing variables by value. Question: But What about books claiming that vari...

This is a Program for Linked List using C. The Code contains enough comments to make your life easy. # include < stdio.h > // structure to hold our data // we call it node // has a int 'value' // also has a pointer that points to next node struct node { int value ; struct node * next ; } ; //typdef will save our time //from now onwards 'struct node' will be replaced by NODE typedef struct node NODE ; // you can notice that we are passing NODE** to insert // Why???? // The answer is simple // since we will be passing the head pointer to the function // and head pointer can be modified in insertion operation // so we must pass a NODE** // reason being if we pass a NODE* to function // its value will be restored after function has returned // hence even if have modified head pointer, it will be restored // so we pass NODE** //------------------ // v is the value to be inserted void insert ( NODE * * base , int v ) {...

Finding Armstrong number is again a great exercise for students The exercise involves clever use of modulus operator to extract the digits and then using those digits to perform calculations.

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.

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.

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 ".

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 ...

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 recu...

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 r...

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 ; ...

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));         ...

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 ,...

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++

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.

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).

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).

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.

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

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 ...

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