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example 1: View this gist on GitHub example 2: View this gist on GitHub

pointer to pointer is nothing but one pointer is holding anther pointers memory location. declaration of pointer to pointer  data_type ** pptr;   initilization of pointer to pointer pptr = &ptr;   accessing value of pointer to pointer  **pptr; Example:  

pointers pointers is one of the data type that use to store memory location of the already declared data type, to store integers we have int data type, to store floating point values we have float data type, to store characters we have char datatypes, as like to store memory of something we have pointers data types. rule for the pointers are it can hold memory of same data type, means if we want to store int data types memory then we have to use int pointer and for char we have to use char pointer you got the point... Declaration of pointers:  data type * variable_name ; Example: int * ptr ; Initialization  of pointers: pointer = &variable name  // now pointer holds memory location of variable ptr = &a; Accessing the value at memory  by using * operator *ptr gives value stored in that location declaration and Initialization of pointer: // declare ptr and store memory of variable togatore data_type * ptr = & varia...

recursion vs iterative approach Iterative     Recursive In iteration, a problem is converted into a train of steps that are finished one at a time, one after another Recursion is like piling all of those steps on top of each other and then quashing them all into the solution. With iteration, each step clearly leads onto the next In recursion, each step replicates itself at a smaller scale, so that all of them combined together eventually solve the problem Any iterative problem is solved recursively Not all recursive problem can solved by iteration does not use Stack It uses Stack

Two-dimensions array Two-dimension arrays are nothing but the arrays as elements of one array.rather then storing the data if we store the arrays in elements then it becomes 2D array. 2D arrays are also similar to the matrix. Declaration of 2D array: Declaration of  2D arrays is quite similar to declaring the one-dimension array, here we also need to specify the size of the second array. syntax: data_type name_of_array [ size_of_raw ][ size_of_colomn ]; example: int  arr[ 2 ] [ 2 ]; it declare 2 X 2, 2-D array. int arr [ 3 ][ 2 ]; its declare 3 X 2, 2-D array. Declaration of 2D array with initializing elements: 1 int arr[ 3 ][ 4 ] = {  {0 ,1, 2, 3}, { 4, 5, 6, 7}, { 8, 9, 10, 11} }; This method first declares the 3 X 4 array then assign value to them according to the position.in this case arr[ 0 ][ 0 ] to arr [ 0 ][ 3 ] is assigned as 0,1,2,3 then arr[ 1 ][ 0 ] to arr [ 1 ][ 3 ] is assigned as 4, 5, 6, 7  and arr[ 1 ][ 0 ] to arr [ 1 ][ 3 ] is assigned as 8, 9,...

An Array is group similar data of one particular data types, the array's elements are continuous in nature when the array is declared the location of the array elements is continuous in memory. advantage of the array is we can assess the similar type of data by using only one variable and as the elements of an array are continuous in memory we can assess the element just by knowing the address of the first element we will see that in pointers. We access the elements of the array by the index in c programming the index of the array starts from 0 to N-1,  where  N is the length of the array. For example, if we want to access the first element of the array then we can use array[ 0 ],  and array[ 4 ] gives us the fifth element of the array. here the 0 and the 4 is the index for the first and the fifth element of the array. Declaration of array: Declaration of the array is the same as declaring a variable of any other data type, but in the case of an array we need to men...

A string is nothing but an array of characters, the difference between the string and the array of character is the string is terminated by the null character "\0". we don't need to add the null character at the end of the strings compiler do that for us when the code is compiling. In string, each character is going to take one byte and one extra byte is required to store the null character. so the size of the string is always going to the length of string + 1 bytes. Declaration of string: Declaration of sting is the same as the declaration of an array. but this time the data type is going to char because we are going to store characters inside the string. char  array_mane[size]; we need to include the null character in the size. example: char name[12]; char array[ 5 ]; Declaration of string with initializing elements: 1 char name[15] = { 'M' , 'y' , 'c', 'o', 'l', 'l', 'e', 'g', 'e', 'b...

calling a function calling a function is a method to invoking the function. we can invoke function by two method call by value call by reference call by value In this method we pass the value or parameter while we calling the function and the parameter's value is copied to the actual function's parameters in your example the value of x and y are copied to local variable x and y of function Call by reference  in this method we pass the memory location of variable as parameter when we calling the function. in your example the memory location of x and y is stored into the a and b then we assessing the values at a and b by using * operator to check maximum out of them. Example: View this gist on GitHub

String Functions Function Use strlen Finds length of a string strlwr Converts a string to lowercase strupr Converts a string to uppercase strcat Appends one string at the end of another strncat Appends first n characters of a string at the end of another strcpy Copies a string into another strncpy Copies first n characters of one string into another strcmp Compares two strings strncmp Compares first n characters of two strings strcmpi Compares two strings without regard to case ("i" denotes that this function ignores case) stricmp Compares two strings without regard to case (identical to strcmpi) strnicmp C...

Operators precedence: It defines the order of evaluation of operators in an expression. Associativity defines the order in which operators of the same precedence are evaluated in an expression. Associativity can be either left to right or right to left. Operator precedent example: 10 + 20 * 30 Now here addition operator has lower precedence and multiplication operator has higher precedence, there for the multiplication operator evaluate first and our equation became 10 + 60 is equal to 70 Here 10+20*30 is calculated as 10+(20*30) is equal to 70 Operator Associativity: Example: '*' and '/' have the same precedence and their associativity is left to right. 100/10*10 is evaluated as (100/10)*10 here / and * have the same precedence but left to right associativity so division operator evaluate first because it comes first from the left side and then the multiplication operator is evaluated 100/10  *10 10* 10 100 Example: 100 + 100/10 - 2 *10 will be evaluated as follows Ste...

prototype of function: prototype of the function is just the basic format of function, in the prototype we just decide datatype of function according to the return type of function and which type data type's and how many arguments is going to take when we want to execute the function. Simply, the prototype is a blueprint of your function. we put all prototype at top of code before the declaration of all functions including the main function because when the code is compiled the prototype is gives promise to the compiler that the function is declared anywhere in the program. Don't worry if you don't get it, its became more clear with an example. syntax: ReturnType Function_Name(argument1, argument2, argument3 , ...) Examples: int max(int a,int b,int c); void mul( float x, float y ); View this gist on GitHub

Functions In C programming language, the user just needs to call the function whenever the user wants to use the function. The example of system-defined functions are printf( ),scanf( ),getsThe functions are known as giving some output for one particular input or argument, we already work with functions like main( ), printf( ),scanf( ) in your  c programs. functions in C are use full in case of reducing code, to improve readability and reuse of code. If we want to perform a certain task frequently with different-different values or parameters then the use of function is convenient for us. It helps to reduce, reuse and improve the readability of your program. there are two types of functions system-defined functions user-defined functions system-defined functions: system-defined functions are already defined by the ( ),puts( ),pow( )... that are already defined by the system we just need to include the file/library that contains the function declaration for...

example: Factorial of number:

Recursion: recursion means function calling it self. when function call it self in function definition it called as recursion. example of recursive function: factorial of number Fibonacci series marge and quick sort And many more... lets understand recursion with example: To understand recursion well lets understand first about stack stack: stack is used to store value and for that stack follows certain rules as LIFO or FILO mean whatever last value is stored it give that value fist ( last in first out) and value that stored first it given at last( first in first out ) both are same in logic way. Don't worry if you face any problem to understand stack it become more clear when we refer examples.  

Header Files Header Files are already written files that simplify your work for example for i/o we have stdio.h header file by using that we can simply input and output stuff to the console. header files have .h extension with it and it is one of the example of modularity of c language, there are many header files are available in c language. stdio.h   defines core input output functions string.h  defines string handling function math.h  defines common mathematical functions and many more... To use these header files, first  we include them in your program and then we can start using their features syntax: #include <headder_filename.h> OR #include "header_filename.h"

Variable in C Variable is a named location in a memory where a program can manipulate the data. This location is used to hold the value of the variable. Different types of variables require different amounts of memory. The value of the variable may get change in the program Variable Declaration: Datatype variable_name; or for multiple variable declarations of same Data type use Datatype variable_1, variable_2, variable_3; When variables are declared the garbage value is assigned to it according to is datatype. Difference between variable declaration and definition. Variable declaration refers to the part where a variable is first declared or introduced before its first use. Variable definition is the part where the variable is assigned a memory location and a value. Howhere the declaration and definition are done together. #include<stdio.h> int main() { // declaration and definition of ...

Typecast is basically a conversion from one type to another. There are two types of type conversion. Implicit type conversion (Type conversion) Explicit type conversion (Typecasting) 1). Implicit type conversion (type conversion) Implicit type conversion is also known as automatic type conversion, Done by the compiler on its own generally takes place when in an expression more then one data type is present in such condition type conversion (Promotion) takes place to avoid loss of data. All the data types of the variables are upgrades to the data type of the variable with the largest data type. boll-> char -> short int -> int -> unsigned int -> long -> Unsigned -> long long -> float -> double -> long double It is possible for implicit conversions to lose information signs can be lost  (When signed is implicitly converted to unsigned) and overflow can occur ( When long long is implicitly converted to float) 2). Explicit type conversion ...

goto statements goto statements are one of the jump statements, by using the goto statement we can jump anywhere in both up and down direction, but the scope of the goto statement is locally so we can jump within a function only.              

break break statements are useful when we want to break your loop or we want to exit the loop when we reach a specific condition. if the break statement is executed then the control moves on the next statement after the loop we can say that the beak statement work as a forward jump in your program. example: //Break #include <stdio.h> int main () { int a; while (1) { printf("enter the number:"); scanf("%d", &a); if ( a == 0 ) break; } return 0; } This program runs until we not provide 0 as input continue continue statement is used when we want to skip some part of that particular iteration or iteration and we want to execute the next iteration of the loop. when the continue statement is executed the control jump on the next statement in the loop. we can say that the continue statement is working like a backward jump in your program. example: //Continue statement #include <stdio.h> int main () { int a,sum = 0; for (a = 0...

Control Structure with Loops: Loops are used to reduce your work, it generally helps us by not writing the stuff over and over when we want to do some type of work at a particular time. There are mainly three types of loops for loop, while loop and do-while loop. let's learn them one by one, firstly we are going to learn for loop then while loop and at last, we go through the do-while loop For Loop : Syntax: for(initialization ; condition ; reinitialization ){ Statements to be run for this particular loop } Okay, Now here "initialization" means from where you want to start your loop Condition means you need to specified condition here, in looping where the condition becomes false control is pass to the next statement and now we exited from a loop. what if the condition becomes true, oh yes when the condition becomes true then loops statements will be executed and the process of reinitialization is done after that. ...