Explain strchr() and strstr() function with example.

strchr() function-This function returns pointer to a position of the first occurence of specified character in the given string.
syntax
chp=strchr(string,ch)   
chp is the pointer,ch is the character to be find in the string

Write a program to find a character in the string using strchr() function.

#include<stdio.h>
#include<conio.h>
main()
{
char string[10],*chp,ch;
clrscr();
printf("Enter the string");
gets(string);
printf("\n Enter the character to be find in the string:");
ch=getchar();
chp=strchr(string,ch);
if(chp)
    {
    printf("\n Character %c is found in the string",ch);
    }
        else
    {
    printf(""\n Character %c is not found in the string",ch);
    }
}
Output
Enter the string:Hello Begginers
Enter the character to be find in the string:r
Character r is found in the string

strstr() function-This function finds the second string in the given string.
syntax
strstr(string1,string2)

Write a program to find a character in the string using strchr() function.

#include<stdio.h>
#include<conio.h>
main()
{
char string1[10],string2[10],*chp;
clrscr();
printf("Enter the first string");
gets(string1);
printf("\n Enter the second string to be found in the first string:");
gets(string2);
chp=strtr(string1,string2);
if(chp)
    {
    printf("\n second string %s is found in the first string",string1);
    }
        else
    {
    printf(""\n second string %s is not found in the first string",string2);
    }
}
Output
Enter the first string:Hello Begginers
Enter the second string to be found in the first string:Hello
second string Hello is found in the first string

Explain strdup() function.

strdup() function-This function is used for duplicating the string at allocated memory which is pointed by a pointer variable.
syntax
dup1=strdup(s1) ,where s1 is string and dup1 is pointer
Write a program to enter a string and get its duplicate with strdup() function.
#include<stdio.h>
#include<conio.h>
main()
{
    char string[10],dup1[10];
    clrscr();
    printf("Enter the string:");
    gets(string);
    dup1=strdup(string)
    printf("\n Original string %s \n Duplicate string %s:",string,dup1);
}
Output
Enter the string:Good Day
Original string Good Day
Duplicate string Good Day
   
   



 

Explain strlwr(),strupr() function with example.

strlwr() function-This function converts any string to a lower case.
syntax
strlwr(upper);

Write a program to convert uppercase string to lowercase.
#include<stdio.h>
#include<conio.h>
main()
{
    char upper[10];
    clrscr();
    printf("Enter the string in uppercase:");
    gets(upper);
    printf("After strlwr(): %s",strlwr(upper));
}
Output
Enter the string in uppercase: ABCD
After strlwr(): abcd


strupr() function-This function converts any string to a upper case.
syntax
strupr(lower);

Write a program to convert lowercase string to uppercase.
#include<stdio.h>
#include<conio.h>
main()
{
    char lower[10];
    clrscr();
    printf("Enter the string in lowercase:");
    gets(lower);
    printf("After strupr(): %s",strupr(lower));
}
Output
Enter the string in uppercase: abcd
After strlwr(): ABCD

Explain stricmp(),strcmp(),strncmp() function.

stricmp() function-This function compares between two strings,it doesn't discriminates between lower and upper case.
syntax
stricmp(source string,destination string)

Write a program to compare between two strings.
#include<stdio.h>
#include<conio.h>
main()
{
    char s1[10],s2[10];
    int diff;
    clrscr();
    printf("Enter the source string:");
    gets(s1);
    printf("Enter the destination string:");
    gets(s2);
    diff=stricmp(s2,s1);
    if(diff==0)
        {
            printf("Two strings are identical");
        }
        else
        {
            printf("Two strings are not identical");
        }
}
Output
Enter the source string:HELLO
Enter the destination string:hello
Two strings are identical


strcmp() function-This function compares between two strings,it does discriminates between lower and upper case.
syntax
stricmp(source string,destination string)

Write a program to compare between two strings.
#include<stdio.h>
#include<conio.h>
main()
{
    char s1[10],s2[10];
    int diff;
    clrscr();
    printf("Enter the source string:");
    gets(s1);
    printf("Enter the destination string:");
    gets(s2);
    diff=strcmp(s2,s1);
    if(diff==0)
        {
            printf("Two strings are identical");
        }
        else
        {
            printf("Two strings are not identical");
        }
}
Output
Enter the source string:HELLO
Enter the destination string:hello
Two strings are not identical

strncmp() function-This function compares between two strings upto specified length.
syntax
stricmp(source string,destination string,n)

Write a program to compare between two strings upto specified length.
#include<stdio.h>
#include<conio.h>
main()
{
    char s1[10],s2[10];
    int n,diff;
    clrscr();
    printf("Enter the source string:");
    gets(s1);
    printf("Enter the destination string:");
    gets(s2);
    printf("Enter length upto which comparison is to be made");
    scanf("%d",&n);
    diff=strcmp(s2,s1,n);
    if(diff==0)
        {
            printf("Two strings are identical upto %d characters");
        }
        else
        {
            printf("Two strings are not identical");
        }
}
Output
Enter the source string:HELLO
Enter the destination string:hello
Two strings are not identical

Explain strcpy() and strncpy() function with example.

strcpy() function-It copies contents of one string to another.
Syntax
strcpy(destination,source)  ,where source string is copied to destination string.

Write a program to copy contents of one string to another by using strcpy().
#include<stdio.h>
#include<conio.h>
main()
{
    char s1[10],s2[10];
    clrscr();
    printf("Enter the string:");
    gets(s1);
    strcpy=(s2,s1);
    printf("\n Original string :%s",s1);
    printf("\n Duplicate string :%s",s2);
}
Output
Enter the string:Ragu
Original string:Ragu
Duplicate string:Ragu

strncpy() function-This function copies specified length of characters from source to destination string.
syntax
strncpy(destination,source,n) ,where n is the specified length

Write a program to copy source string to destination string with given length.
#include<stdio.h>
#include<conio.h>
main()
{
    char s1[10],s2[10];
    int n;
    clrscr();
    printf("Enter the source string:");
    gets(s1);
    printf("Enter the destination string:");
    gets(s2);
    printf("Enter number of characters to be replaced in destination string:");
    scanf("%d"&n);
    strcpy=(s2,s1,n);
    printf("\n Original string :%s",s1);
    printf("\n Duplicate string :%s",s2);
}
Output
Enter the source string:Wonderful
Enter the destination string:beautiful
Enter number of characters to be replaced in destination string:6
Enter the source string:Wonderful
Enter the destination string:wonderful

Explain strlen() function.

strlen() function-It counts number of characters in a string.
Syntax
l=strlen(string)   ,where l reads the count of characters

Write a program to read a string through keyboard.Determine length of the string.

#include<stdio.h>
#include<conio.h>
main()
{
    char string[10];
    int string,l;
    printf("Enter the string:");
    gets(string);
    l=strlen(string);
    printf("Entered name is %s and its length is %d",string,l);
}
Output
Enter the string:
Rohini
Entered string is Rohini and its length is 6

Explain string with different formats.

String
Group of characters,digits,symbols enclosed within quotation marks are called strings.The C compiler inserts NULL(\0) character automatically at end of the string.
Different formats of initialization of string
char name[]="INDIA";
or
char name[]={'I','N','D','I,'A','\0'};
or
char name[]={{I},{N},{D},{I},{A}};

Write a program to print "INDIA" by using different formats of initialization of array.
#include<stdio.h>
#include<conio.h>
#include<string.h>
main()
   {
    char a1[]={'I','N','D','I''A','\0'};
    char a2[]="INDIA";
    char a3[6]={{I},{N},{D},{I},{A}};
    clrscr();
    printf("\n Array1=%s",a1);
    printf("\n Array2=%s",a2);
    printf("\n Array3=%s",a3);
   }
Output
Array1=INDIA
Array2=INDIA
Array3=INDIA

Write a program to display string 'PRABHAKAR 'using different formats.
#include<stdio.h>
#include<conio.h>
#include<string.h>
main()
{
char a[]="PRABHAKAR";
clrscr();
printf("  %s  \n ",a);
printf(" %.5s \n ",a);
printf(" %.8s \n ",a");
printf(" %.15s \n ",a);
printf(" %-10.4s  \n",a);
printf(" %11s \n ",a);
}
Output
PRABHAKAR
PRABH
PRABHAKA
PRABHAKAR
PRAB
PRABHAKAR

Print elements of character array given with while loop (help of Null character).

#include<stdio.h>
#include<conio.h>
main()
{
    char a[]="Have a nice day";
    int i=0;
    clrscr();
    printf("Elements of the array:");
    printf("\n");
    while(a[i]!='\0')
        {
        printf("  %c ",a[i]);
        i++;   
        }

}
Output
Elements of the array:
Have a nice day

Explain two dimensional array with example.Write a program to print a matrix and its transpose.

Two dimensional array-It is a collection of a number of one-dimensional arrays.Each row can be thought of as a one-dimensional array.
It is thought as a rectangular display of elements with rows and columns.
        column1        column2     column3
row1        x[0][0]        x[0][1]        x[0][2]
row2        x[1][0]        x[1][1]        x[1][2]
row3        x[2][0]        x[2][1]        x[2][2]

Write a program to display elements of two dimensional array.
#include<stdio.h>
#include<conio.h>
main()
{
int a[3][3]={{1,2,3},{4,5,6},{7,8,9}};
printf("Elements of an array");
for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
            {
            printf(" \t %d ",a[i][j]);
            }
        printf(" \n ")
           
    }
   Output
   1 2 3
   4 5 6
   7 8 9

Write a program to enter elements of a matix with order 3x3 and print the matrix.


#include<stdio.h>
#include<conio.h>
main()
{
int a[3][3];
printf("Enter elements of an array");
for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
            {
            scanf(" \t %d ",&a[i][j]);
            }
        printf("\n")
    }
for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
            {
            printf(" \t %d",a[i][j]);
            }
        printf("\n")
    }
       Output
    Enter elements of an array
       1 2 3
       4 5 6
       7 8 9
Write a program to enter elements of a matix with order 3x3 and display its transpose.

#include<stdio.h>
#include<conio.h>
main()
{
int a[3][3];
printf("Enter elements of an array");
for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
            {
            scanf(" \t %d ",&a[i][j]);
            }
        printf("\n")
    }
for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
            {
            printf(" \t %d",a[i][j]);
            }
        printf("\n")
    }
printf("Transpose of matrix");
for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
            {
            printf(" \t %d",a[j][i]);
            }
        printf("\n")
    }
}
    Output
Enter elements of an array
    1 2 3
    4 5 6
    7 8 9
Transpose of matrix
    1 4 7
    2 5 8
    3 6 9

Explain array with one dimensional array example

Array-It is a set of unique variables with same data type located in continous memory locations.

Declaration of array
int a[5];
Here set of 5 elements with integer data type is stored in the array a.

initialization of array
int a[5]={1,2,3,4,5}

Important point-
(a)Array elements are called by array names.
array element 1 called by array name a[0],array element 2 called by array name a[1],array element 3 called by array name a[2],
array element 4 called by array name a[3],array element 5 called by array name a[4]
(b)Any particular element of an array can be modified seperately without disturbing other elements.
Example-
int a[5]={1,2,3,8,5}
To carry out this task the statement a[3]=4 can be used to change element 8 to 4 from array a[5].
(c)Starting memory location of array a assumed 2000 then next element located in 2002 because each integer element requires 2 bytes.
So character-1 byte,integer-2bytes,float-4 bytes,long-4 bytes,double-8 bytes.

Character array-They are called as strings.Here NULL('\0') character is automatically added at the end.
NULL acts as an end of the character array when compiler reads it .

Write a program to display elements of one dimensional character array with address.
#include<stdio.h>
#include<conio.h>
main()
{
int i=0;
char name[6]={'A','R','R','A','Y'};
printf("Character and memory location");
while(name[i]!='\0')
    {
        printf("    \n  %c \t %u   ",name[i],&name[i]);
        i++;
    }
}
Output
Character and memory location
A    4054
R    4055
R    4056
A    4057
Y    4058

Explain each decision statements with example.

It checks the condition,then executes its sub block.

if statement-It checks the condition,if condition is true then executes its sub block.
Otherwise when condition is false,the compiler skips lines within the if block.
It is enclosed in curly braces.
Use curly braces even with a single statement.

syntax
if(condition is true)
{
statement;
}

Write an example for if statement checking if entered number is less than 10.
#include<stdio.h>
#include<conio.h>
main()
 {
  clrscr();
  int a;
  printf("Enter the number:");
  scanf("%d",&a);
  if(a<10)
   {
    printf("Entered number is less than 10");
    else
    printf("Entered number is not less than 10");
   }
}

Output

Enter the number:5

Entered number is less than 10

if else statement-It has two blocks.if condition is true first block is executed otherwise if condition is false else block is executed.

syntax
if(condition is true)
  {
   statement1;
  }
 else
  {
  statement2;
  }

Write example for if else statement.Read values of a,b,c Add and check after addition if it is in the range of 100 & 200 or not.
 
#include<stdio.h>
#include<conio.h>
main()
 {
  clrscr();
  int a,b,c;
  printf("Enter the numbers a b c:");
  scanf("%d %d %d",&a.&b,&c);
  printf("\n a=%d b=%d c=%d",a,b,c)
  d=a+b+c;
  if(d>=100 & d<=200)
    {
    printf("\n Sum is in between 100 and 200");
    else
    printf("\n Sum is not in between 100 and 200");
    }
 }

Output
Enter the numbers a b c: 50 50 20
a=50 b=50 c=20
Sum is in between 100 and 200

nested if statement-If condiion is true then first block is executed.Otherwise in else block condition is checked with the if statement..

syntax
if(condition is true)
  {
   statement1;
  }
   else if (condition is true)
              {
              statement2;
              }
            else
              {
              statement3;
              }

Write an example for nested if else statement where find largest among 3 numbers.

#include<stdio.h>
#include<conio.h>
main()
 {
  clrscr();
  int a,b,c;
  printf("Enter the numbers a b c:");
  scanf("%d %d %d",&a.&b,&c);
  printf("\n a=%d b=%d c=%d",a,b,c)
 
  if(a>b)
    {
      if(a>c)
          {
          printf("\n Largest number is %d",a);
          }
          else
          {
          printf("\n  Largest number is %d",c ");
          }

    }
  else
    {
       if(c>b)
           {
           printf("\n Largest number is %d",c);
           }
           else
           {
          printf("\n  Largest number is %d",b ");
           }

   }
 
Output

Enter the numbers a b c:10 20 30
Largest number is 30

break statement-break skips from the loop in which it is defined and then goes automatically to first statement after loop.

continue statement-It is used for continuing in next iteration of loop statement and it skips the statement after this statement.

goto statement-Where label is the position where the control is to be transfered.

syntax
goto label;

where label name must start with any character

Write an example of goto statement checking the number whether even or odd.
   
    #include<stdio.h>
    #include<conio.h>   
    main()
     {
    int a;
    clrscr();    
    printf("Enter the number:");
    scanf("%d %d",&a);
      if(a%2==0)
             {
             goto even:
             }
               else
             {
             goto odd;
             }
    even:
    printf("\n %d is even");
    return;
    odd:
    printf("\n %d is odd");
    }

       Output
     
 Enter the number:4
       4 is even

Switch statement-Used to make a choice from a number of options.It need only one argument of any data type,which is checked with many case options.
   
    syntax
    switch(variable)
        {
        case constant a:
        statement;
        break;
        case constant b:
        statement;
        break;
        default:
        statement;
        }
Write an example for switch statement showing functions like addition ,subtraction
,multiplication,division,remainder.
    #include<stdio.h>
    #include<conio.h>
    main()
     {
          clrscr();
          int a,b,c,ch;
        printf("0 \n TERMINATED BY CHOICE");
          printf("1 \n FOR ADDITION");
          printf("2 \n FOR SUBTRACTION");
          printf("3 \n FOR MULTIPLICATION");
          printf("4 \n FOR DIVISION");
          printf("5 \n FOR REMAINDER");
          printf("6 \n FOR EXIT");
          printf("\n ENTER YOUR CHOICE")
        scanf("%d",&ch);
            if(ch<=6 && ch>=0)
                {
                    printf("Enter 2 numbers:");
                    scanf("%d %d",&a,&b);
                }
        switch(ch)
        {
       
        case 1:
        c=a+b;
        printf("ADDITION:%d",c);
        break;
       
        case 2:
        c=a-b;
        printf("SUBTRACTION:%d",c);
        break;

        case 3:
        c=a*b;
        printf("MULTIPLICATION:%d",c);

        case 4:
        c=a/b;
        printf("DIVISION:%d",c);
        break;
       
        case 5
        c=a+b;
        printf("REMAINDER:%d",c);
        break;

        case 0:
        printf("\n TERMINATED BY CHOICE");
        exit();
        break;
        default:
        printf("Invalid choice");
           }
    }
       

Explain increment operator with example.

The operator ++ adds one to its operand.
x=x+1 can be written as x++ or ++x
If ++ is used as prefix then value of variable will be increased first.
If ++ is used as suffix then value of variable will be increased later.

Write a program to show effect of increment operator as a prefix.

#include<stdio.h>
#include<conio.h>
main()
{
clrscr();
int x=10,y=10,z;
z=x* ++y;  /* y is increased first then used for multiplication */
printf("Value of z = %d",z);

output
Value of z=110


Write a program to show effect of increment operator as a suffix.

#include<stdio.h>
#include<conio.h>
main()
{
clrscr();
int x=10,y=10,z;
z=x*y++;  /* First multiplication then y is increased*/
printf("Value of z = %d",z);

output
Value of z=101


Write a program to show '&' operator.

#include<stdio.h>
#include<conio.h>
main()
{
clrscr();
int x=2;
float y=2;
printf("Address of x=%u,Address of y=%u",&x,&y);
}

output
Address of x=4066,Address of y=25096

Explain conditional operator with example.

Conditional operator
Here if given condition is true then exp1 is evaluated else exp2.

syntax
condition?(exp1) : (exp2);

Write a program to show conditional operator
#include<stdio.h>
#include<conio.h>
main
int x=2;
()
{
clrscr();
printf("Result=%d",1==2?4:5);
}

output
Result=5

Explain comma operator with example.

It is used to separate 2 or more expressions.
It has lowest priority among all operators.

Write a program to show comma operator

#include<stdio.h>
#include<conio.h>
main()
{
clrscr();
printf("Addition =%d \n Subtraction=5d",3+2,3-2);
}
output
Addition=5
Subtraction=1

Explain Logical operator with example.

It check logical relation between two expressions.If relation is true it returns 1 otherwise 0.
The operators are logical AND(&&),logical OR(||),logical NOT(!=).

Write a program to print logic 1 if input character is capital otherwise 0.

#include<stdio.h>
#include<conio.h>
main()
{
char x;
int y;
clrscr();
printf(" \n Enter a character ");
scanf(" %c ",&x);
y=( x>=65 && x<=90 ? 1:0 );
printf(" Y : %d ",y );


}

Output
Enter a character : A
Y : 1
Enter a character : a
Y : 0

Write a program to display 1 if inputted number is between 1-100 otherwise 0.Use logical AND(&&) operator.

#include<stdio.h>
#include<conio.h>
main()
{
char x;
int y;
clrscr();
printf(" \n Enter a number:");
scanf(" %c ",&x);
y=( x>=1 && x<=100 ? 1:0 );
printf(" Y : %d ",y );
}

output
Enter a number:5
Y= 1


Write a program to display 1 if inputted number is either 1  or 100 otherwise 0.Use logical OR(||) operator.

#include<stdio.h>
#include<conio.h>
main()
{
char x;
int y;
clrscr();
printf(" \n Enter a number:");
scanf(" %c ",&x);
y=( x==1 || x==100 ? 1:0 );
printf(" Y : %d ",y );
}

output
Enter a number:5
Y=0
Enter a number:100
Y=1

Write a program to display 1 if inputted number is between 1-100 otherwise 0.Use logical AND(&&) operator.

#include<stdio.h>
#include<conio.h>
main()
{
char x;
int y;
clrscr();
printf(" \n Enter a number");
scanf(" %c ",&x);
y=( x>=1 && x<=100 ? 1:0 );
printf(" Y : %d ",y );
}

output
Enter a number:5
Y= 1

Write a program to display 1 if inputted number is not 100 otherwise 0.Use logical NOT(!=) operator.

#include<stdio.h>
#include<conio.h>
main()
{
char x;
int y;
clrscr();
printf(" \n Enter a number");
scanf(" %c ",&x);
y=( x!=100 ? 1:0 );
printf(" Y : %d ",y );
}

output
Enter a number:100
Y= 0

Explain Relational operator with example.

It check relation between two constant values.If relation is true it returns 1 otherwise 0.
The operators are >=,<=,<,>,==,!=.


Write a program to use all relational operator and display thier return values.

#include<stdio.h>
#include<conio.h>
main()
{
clrscr();
printf("  \n Condition : Return value  ");
printf("  \n 10!=10 :%5d  ",10!=10);  /* not equal to */
printf("  \n 10<=10 :%5d  ",10<=10);  /* less than or equal too */
}

Output

Condition : Return Value
   10!=10 : 0
   10<=10 : 1

Explain Input and Output function in C

I/O function

Input function-A program takes data through input function.
Output function-A program displays result on screen through output function

2 Types

a)  Formatted b) Unformatted function

Formatted function-It read and write all types of data types.

2 Types

a) printf( ) b) scanf( )

printf() statement-It prints data values to the console.It need conversion symbols to print  variable values.Here escape sequence \n is used for new line.

scanf() statement-It reads data values.It need conversion symbols to read variable values.
The '&' address operator is used to indicate memory location of variable,so that value read should be placed in that location.

Unformatted function-It work with only character data type.
 Types
(a) getchar( ) (b) putchar( ) (c) getch( ) (d) getche ( ) (e) gets( ) (f) puts( )

Explain arithematic operator in C

binary arithmetic operator-This is used for calculation between two constant values.They are +,-,*,/,%.
unary arithmetic operator-This is used for calculation with one value.They are unary minus(-),increment(++),decrement(--),address operator(&),sizeof.

Write a program to show effect of increment operator as a prefix and suffix.

#include<stdio.h>
#include<conio.h>
main()
{
int a,b,x=10,y=20;
clrscr();
a=x * ++y;  /* increment as prefix,here  value of y is increased  and then used for multiplication*/
c=x*y;
b=x * y++; /*increment as suffix,here  after multiplication y is increased */
d=x*y;
printf(" \n %d %d ",a,c,b,d);
}

output


210 210 200 210

address (&) operator-It prints address of variable in memory.
sizeof() operator-It gives bytes occupied by variable.

Write a program to use address (&) operator and sizeof() operator.


#include<stdio.h>
#include<conio.h>
main()
{
int x=2;
float y=2;
clrscr();
printf("\n sizeof(x)=%d bytes,sizeof(y)=%d bytes ",sizeof(x),sizeof(y));
printf("\n Address of x=%u,Address of y=%u",&x,&y);
}


output
sizeof(x)=2,sizeof(y)=4
Address of x=4066,Address of y=25096

Explain variable in C

Variable
A variable is a data name used for storing a data value.
Its value may change during execution.
It should not be a C keyword.
It may be a combination of uppercase and lowercase characters.
Ex-
sUm and SUM both are different.
It should start with a character not a digit
Declare variable
Its declaration should be done in declaration part of C program because it helps in allocating memory.
Syntax-
datatype variablename;
ex-
int age;
int a,b,c;
Initialize variable
Initialization and declaration of variable can be done in same line.
syntax-
datatype varaible = constant;
ex-
int y=2;
Constant variable
To make value of variable constant use keyword const before declaration
ex-
const int m=1;

Explain data types in C

Data types 
They are used to define  variables before its use.As per need different data types are used in C.
For example
a)int is used to define integer numbers
{
int count;
count=4;
}
b)float is used to define floating point numbers
{
float miles;
miles=5.6;
}
c)double is used to define big floating point numbers,it reserves twice the storage for numbers.
{
double atoms;
atoms=25000;
}
d)char defines character
{
char letter;
letter='c';
These are common data types.Others are short,long,signed,unsigned.
short int<int<long int
float<double<long double
signed and unsigned
when a variable is declared as unsigned then negative range of data type is declared as positive.
example
unsigned long int c;
Memory size of different data types
short integer occupies memory of 2 bytes
long integer occupies memory of 4 bytes
signed and unsigned integer occupies memory of 2 bytes
float occupies memory of 4 bytes
double occupies memory of 8 bytes
character occupies memory of 1 byte