String Library functionsThe predefined functions which are designed to handle strings are available in the library string.h. They are −strlen ()strcmp ()strcpy ()strncmp ()strncpy ()strrev ()strcat ()strstr ()strncat ()The strlen () functionIt returns the number of characters in a string.Syntaxint strlen (string name)Example#include main (){    char a[30] = “Hello”;    int l;    l = strlen (a);    printf (“length of the string = %d”, l);    getch (); }Outputlength of the string = 5The strcpy () functionIt is for copying source string into destination string.The length of the destination string >= source string.Syntaxstrcpy (Destination string, Source String);For ... Read More

Arrays of pointers (to strings)Array of pointers is an array whose elements are pointers to the base address of the string.It is declared and initialized as follows −char *a[3 ] = {"one", "two", "three"}; //Here, a[0] is a ptr to the base add of the string "one" //a[1] is a ptr to the base add of the string "two" //a[2] is a ptr to the base add of the string "three"AdvantagesUnlink the two-dimensional array of characters. In (array of strings), in array of pointers to strings there is no fixed memory size for storage.The strings occupy as many bytes as ... Read More

Pointer to functionIt holds the base address of function definition in memory.Declarationdatatype (*pointername) ();The name of the function itself specifies the base address of the function. So, initialization is done using function name.For example, int (*p) (); p = display; //display () is a function that is defined.Example 1We shall see a program for calling a function using pointer to function −#include main (){    int (*p) (); //declaring pointer to function    clrscr ();    p = display;    *(p) (); //calling pointer to function    getch (); } display (){ //called function present at pointer location    printf(“Hello”); ... Read More

Array Of PointersJust like any other data type, we can also declare a pointer array.Declarationdatatype *pointername [size];For example, int *p[5]; //It represents an array of pointers that can hold 5 integer element addressesInitializationThe ‘&’ is used for initializationFor example,int a[3] = {10,20,30}; int *p[3], i; for (i=0; i

Pointers and Arrays A pointer in C is a variable that stores the address of another variable, which can be of any type(char, int, function). In a 32-bit system, the size of the pointer is 2 bytes. An array is a collection of similar data items stored in contiguous memory locations. In C, arrays can store various data types(char, int, double float) as well as specific types(pointer structures). For example, if we need to represent an array of 5 elements we need to create it as - int a [5] = {10, 20, 30, 40, 50}; ... Read More

Pointer is a variable which stores the address of other variable.Pointer declaration, initialization and accessingConsider the following statement −int qty = 179;Declaring a pointerint *p;‘p’ is a pointer variable that holds the address of another integer variable.Initialization of a pointerAddress operator (&) is used to initialize a pointer variable.int qty = 175; int *p; p= &qty;Arithmetic operations using pointersPointer variables can be used in expressions. For example, if pointer variables are properly declared and initialized then the following statements are valid.a) *p1 + *p2 b) *p1- *p2 c) *p1 * *p2 d) *p1/ *p2 Note: There must be a blank ... Read More

If individual elements are to be passed as arguments, then array elements along with their subscripts must be given in function call.To receive the elements, simple variables are used in function definition.Example 1#include main (){    void display (int, int);    int a[5], i;    clrscr();    printf (“enter 5 elements”);    for (i=0; i

ArrayThe array is a group of related items that store with a common name. Following are the two ways of passing arrays as arguments to functions −sending entire array as argument to functionsending individual elements as argument to functionSending entire array as an argument to a functionTo send entire array as argument, just send the array name in the function call.To receive an array, it must be declared in the function header.Example 1#include main (){    void display (int a[5]);    int a[5], i;    clrscr();    printf ("enter 5 elements");    for (i=0; i

Local scopeLocal scope specifies that variables defined within the block are visible only in that block and invisible outside the block.Global scopeGlobal scope specifies that variables defined outside the block are visible up to end of the program.Example#include int r= 50; /* global area */ main (){    int p = 30;    printf (“p=%d, r=%d” p, r);    fun (); } fun (){    printf (“r=%d”, r); }Outputp =30, r = 50 r = 50Scope rules related to functionsA Function is a block of statements that performs a particular task.Variables that are declared within the body of a function ... Read More

Global scopeGlobal scope specifies that variables defined outside the block are visible up to end of the program.Example#include int c= 30; /* global area */ main (){    int a = 10;    printf (“a=%d, c=%d” a, c);    fun (); } fun (){    printf (“c=%d”, c); }Outputa =10, c = 30 c = 30Local scopeLocal scope specifies that variables defined within the block are visible only in that block and invisible outside the block.Variables declared in a block or function (local) are accessible within that block and does not exist outside it.Example#include main (){    int i = ... Read More