C Articles - Page 22 of 95

Pointer to structure holds the address of an entire structure.Mainly, these are used to create the complex data structures such as linked lists, trees, graphs and so on.The members of the structure can be accessed by using a special operator called arrow operator ( -> ).DeclarationFollowing is the declaration for pointer to structure −struct tagname *ptr;For example, struct student *s;AccessingYou can access pointer to structure by using the following −Ptr-> membername;For example, s->sno, s->sname, s->marks;ExampleFollowing is the C program of the pointer structures −#include struct student{    int sno;    char sname[30];    float marks; }; main ( ){   ... Read More

Passing the address of structure as an argument to function −The Address of the structure is passed as an argument to the function.It is collected in a pointer to structure in function header.AdvantagesNo wastage of memory as there is no need of creating a copy againNo need of returning the values back as the function can access indirectly the entire structure and work on it.Example#include struct date{    int day;    int mon;    int yr; }; main (){    struct date d= {02, 01, 2010};    display (&d);    getch (); } display (struct date *dt){    printf("day = ... Read More

Passing individual members as arguments to function −Each member is passed as an argument in the function call.They are collected independently in ordinary variables in function header.Example#include //Declaring structure// struct student{    int s1,s2,s3; }s[5]; //Declaring and returning Function// void addition(int a,int b,int c){    //Declaring sum variable and For loop variable//    int i,sum;    //Arithmetic Operation//    for(i=1;i

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

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

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

Functions are broadly classified into two types which are as follows −predefined functionsuser defined functionsPredefined (or) library functionsThese functions are already defined in the system libraries.Programmer can reuse the existing code in the system libraries which is helpful to write error free code.User must be aware of syntax of the function.For instance, sqrt() function is available in math.h library and its usage is y= sqrt (x), where x= number must be positive.If x value is 25, i.e., y = sqrt (25) then ‘y’ = 5.In the same way, printf() is available in stdio.h library and clrscr() is available in conio.h ... Read More

Problem Applying the software development method to solve any problem in C Language. Solution Find roots of a quadratic equation, ax2+bx+c. There will be 2 roots for given quadratic equation. Analysis Input − a, b, c values Output − r1, r2 values Procedure $r_{1}=\frac{-b+\sqrt{b^2-4ac}}{2a}$ $r_{2}=\frac{-b-\sqrt{b^2-4ac}}{2a}$ Design (Algorithm) Start Read a, b, c values Compute d = b2 4ac if d > 0 then ... Read More

An array of characters is called a string.DeclarationFollowing is the declaration for an array −char stringname [size];For example − char a[50]; string of length 50 charactersInitializationUsing single character constant −char a[10] = { ‘H’, ‘e’, ‘l’, ‘l’, ‘o’ ,‘\0’}Using string constants −char a[10] = "Hello":;AccessingThere is a control string "%s" used for accessing the string till it encounters ‘\0’.The logic used to convert vowels from upper to lower or lower to upper is −for(i=0;string[i]!='\0';i++){    if(string[i]=='a'||string[i]=='e'||string[i]=='i'||string[i]=='o'||string[i]=='u'){       string[i]=toupper(string[i]);    } } printf("The result string with converted vowels is : "); puts(string);ProgramFollowing is the C program using conversion functions ... Read More