arraytypes of array and pointer string in c++.pptx

ARRAY IN C++ -VARSHAA.M MAHESHA.V

WHAT IS ARRAY? • An array is a group of consective memory locations with same name and data type. • Simple variable is a single memory location with unique name and a type. But an Array is collection of different adjacent memory locations. All these memory locations have one collective name and type. • The memory locations in the array are known as elements of array. The total number of elements in the array is called length. • The elements of array is accessed with reference to its position in array, that is call index or subscript.

DECLARATION OF AN ARRAY: Like a regular variable, an array must be declared before it is used. A typical declaration for an array in Visual C++ is: type name [elements];  type is a valid type (like int, float...)  name is a valid identifier  elements field (which is always enclosed in square brackets []), specifies how many of these elements the array has to contain.

EXPLANATION: INT NUM[6] size of the array Base name of type array

ADVANTAGES OF ARRAY:  Arrays can store a large number of value with single name.  Arrays are used to process many value easily and quickly.  The values stored in an array can be sorted easily.  The search process can be applied on arrays easily.

TYPES OF ARRAY: Single dimensional array Two dimensional array Multi dimensional array

ONE DIMENSIONAL ARRAY: A one dimensional array is one in which one subscript /indices specification is needed to specify a particular element of array Declaration : Data_type array_name [size of array ]; Eg: Int num[10];

MEMORY REPRESENTATION: num[0] num[1] num[2] num[3] num[4] num[5] num[6] num[7] num[8] num[9] 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 starting Address of location Total memory in bytes that an array is occupied : Size of array=size of array*size of(base type) Hear, 10*2=20 39 56 23 98 6 56 9 2 54 67

TWO DIMENSIONAL ARRAY: A 2-d array is an array in which each element is itself an array i.e int num[4][3] 0 1 2 0 1 2 3 No of rows No of colu mns No of element in 2-D array =M*N Num [2][1]

MEMORY REPRESENTATION: Total bytes= no of rows*no of columns*size of(base type) Memory reprsentation in 2-D array: char A [2][3] A[0][0] A[0][1] A[0][2] A[1][0] A[1][1] A[1][2] 5001 5002 5003 5004 5005 5006

MULTI DIMENSIONAL ARRAY: An array with dimensions more than two .The maximum limit of array is compiler dependent Declaration: Data_type name [a][b][c][d][e][f]…….[n]; Array of 3 or more dimensional are not often use because of huge memory requirement and complexity involved

ARRAY INITIALIZATION: C++ provides the facility of array initialization at the time of declaration .General form of array initialization is as: Type array_name[size 1]…..[size N] ={vale list}; Eg: Int days_month[12]={31,25,29,03,31,19,20,31,18,20,31,29}; Char string[6]={‘a’,’r’,’g’,’y’,’d’,’0’}; 2-D array are also initialized in same way as linear array Int cube[4][2]={ 1,3, 4,6, 9,37, 5,78 };

UNSIZED ARRAY INITIALIZATION: C++ allowed you to skip the size of array in an array initialization statement C++ automatically create an array big enough to hold all the initializers present Char S1[] =“ first string ”; you skip the size, you must give list of initializers so that C++ can calculate the size of array Int val []={3,5,6,2,8,9,6,4}; Int cube [] [2] ={ 1,3, 67,7, 6,87, };

STRING AS ARRAY: C++ does not have a String data type ,it impairments string as 1-D character Arrray .A string as a character array is terminate by a null character ‘0’ Char str 1 [11]; Char square [][]={ ‘first string’, ‘second string’, ‘third string’ };

SORTING ARRAYS: Sorting is a process of arranging the value of array in a particular order. An array can be sorted in two order. o Ascending Order o Descending Order

String  C++ strings are sequences of characters stored in a char array.  Strings are used to store words and text.  String index starts with o last character of string in null(0)  Strings in C++ can be defined either using the std::string class or the C-style character arrays.

C Style Strings  These strings are stored as the plain old array of characters terminated by a null character ‘0’. They are the type of strings that C++ inherited from C language.  Syntax:  Char str[]=“greeksforgreeks”

 // C++ Program to demonstrate strings  #include <iostream>  using namespace std;  int main()  {  char s[] = "GeeksforGeeks";  cout << s << endl;  return 0;  }  Output:GreeksforGreeks

 std::string Class  These are the new types of strings that are introduced in C++ as std::string class defined inside <string> header file. This provides many advantages over conventional C-style strings such as dynamic size, member functions, etc.  Syntax:std::string str("GeeksforGeeks");

String manipulator functions  C++ supports a wide range of functions that manipulate null-terminated strings. These are:  strcpy(str1, str2): Copies string str2 into string str1.  strcat(str1, str2): Concatenates string str2 onto the end of string str1.  strlen(str1): Returns the length of string str1.  strcmp(str1, str2): Returns 0 if str1 and str2 are the same; less than 0 if str1<str2; greater than 0 if str1>str2.  strchr(str1, ch): Returns a pointer to the first occurrence of character ch in string str1.  strstr(str1, str2): Returns a pointer to the first occurrence of string str2 in string str1.

Pointer  Pointer is a variable that holds the memory address of another variable.  Declaration of array is  datataype *pointer-variable;  Pointer variable is the name of the pointer, datatype refers to valid c++ datatypes.

 Int *ptr,a; //declaration  Ptr=&a; //initialization  Ptr contains address of variabler a,& is addess operator or reference operator to retrieve the address of the variable.  Example int a=10;  int *ptr=&a;

Pointer arithmetic  Pointer arithmetic means performing arithmetic operations on pointers. It refers to the operations that are valid to perform on pointers. Following are the arithmetic operations valid on pointers in C++:  Incrementing and Decrementing Pointers  Addition of Constant to Pointers  Subtraction of Constant from Pointers  Subtraction of Two Pointers of the Same Type  Comparison of Pointers

 Incrementing and Decrementing Pointer in C++  Incrementing or decrementing a pointer will make it refer to the address of the next or previous data in the memory. This process differs from incrementing and decrementing numeric data.

Incrementing a Pointer  Incrementing a pointer will depend on the type of variable address stored in the pointer. If the pointer stored the address of the integer type variable then the size of the integer pointer can be 4 bytes.  For example, If a pointer holds the address 1000 and we increment the pointer, then the pointer will be incremented by 4 or 8 bytes (size of the integer), and the pointer will now hold the address 1004.

 Decrementing a Pointer  When we apply a decrement operation on the pointer then the pointer is decremented by 4 or 8 bytes depending upon the machine.  For example, If a pointer holds the address 1004 and we decrement the pointer, then the pointer will be decremented by 4 or 8 bytes (size of the integer), and the pointer will now hold the address 1000.

 Memory 996 997 998 999 1000 1001 1002 1003 1004

 Addition of Constant to Pointers  We can add integer values to Pointers and the pointer is adjusted based on the size of the data type it points to. For example, if an integer pointer stores the address 1000 and we add the value 5 to the pointer, it will store the new address as:

 Memory 1000 1004 1008 1012 1016 1020 1024 1028 1032 1000 + (5 * 4(size of an integer)) = 1020

 Subtraction of Constant from Pointers  We can also subtract a constant from Pointers and it is the same as the addition of a constant to a pointer. For example, if an integer pointer stores the address 1000 and we subtract the value 5 from the pointer, it will store the new address as:  1000 - (5 * 4(size of an integer)) = 980

 Subtraction of Two Pointers of the Same Datatype  The Subtraction of two pointers can be done only when both pointers are of the same data type. The subtraction of two pointers gives the number of elements present between the two pointers

 Comparison of Pointers  In C++, we can perform a comparison between the two pointers using the relational operators(>, <, >=, <=, ==, !=). We generally use this operation to check whether the two-pointer as pointing to the same memory location or not.

arraytypes of array and pointer string in c++.pptx

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arraytypes of array and pointer string in c++.pptx