Write a program in C top print the pattern

pattern :

                     1
                     2 2
                    3 3 3
                   4 4 4 4
                  5 5 5 5 5

Code :

#include <stdio.h>
#include <conio.h>
void main()
{
int r,s,c;
clrscr();
for(r=1;r<=5;r++)
{
for(s=1;s<=(5-r);s++)
printf(" ");
for(c=1;c<=r;c++)
printf("%2d",r);
printf("\n");
}
getch();
}

output:
                   
                      1
                     2 2
                    3 3 3
                   4 4 4 4
                  5 5 5 5 5

C program to find the sum of a digits of a given number

#include <stdio.h>
#include <conio.h>
void main()
{
  int a,b,c=0;
  clrscr();
  printf("\n Enter any number: ");
  scanf("%d",&a);
  while(a!=0)
  {
    b=a%10;
    a=a/10;
    c=b+c;
  }
  printf("sum of individual digits= %d",c);
  printf("\n\n Thanks For Visiting");
  printf("\n www.information-technology008.blogspot.in");
  getch();
}

Input: 
             Enter any number: 567
Output:
           sum of individual digits= 18

What is C programming language ?

C is a programming language developed at AT and T's Bell laboratories of USA in the year of 1972 . It was designed and written by a man named Dennis Ritchie . In the late seventies C began to replace the more familiar languages of that time like PL/I , ALGOL , Etc no one pushed C . It was not made the " Official " Bell Labs language. Thus, without any advertisement C's reputation spread and its pool of users grew. Ritchie seems to have been rather surprised that so many programmers preferred C to older languages like FORTRAN , or PL/I or the newer one like Pascal and APL.    

C programming code to shutdown your computer for Windows XP

#include <stdio.h>
#include <stdlib.h>

main()
{
char ch;

printf("Do you want to shutdown your computer now (y/n)\n");
scanf("%c",&ch);

if (ch == 'y' || ch == 'Y')
system("C:\\WINDOWS\\System32\\shutdown -s");

return 0;
}

C programming code to shutdown your computer for Windows 7

#include <stdio.h>
#include <stdlib.h>

main()
{
char ch;

printf("Do you want to shutdown your computer now (y/n)\n");
scanf("%c",&ch);

if (ch == 'y' || ch == 'Y')
system("C:\\WINDOWS\\System32\\shutdown /s");

return 0;
}

Variables and Arithmetic Expressions in c

The next program uses the formula oC=(5/9)(oF-32) to print the following table of Fahrenheit temperatures and
their centigrade or Celsius equivalents:
1 -17
20 -6
40 4
60 15
80 26
100 37
120 48
140 60
160 71
180 82
200 93
220 104
240 115
260 126
280 137
300 148
The program itself still consists of the definition of a single function named main. It is longer than the one that
printed ``hello, world'', but not complicated. It introduces several new ideas, including comments,
declarations, variables, arithmetic expressions, loops , and formatted output.
#include <stdio.h>
/* print Fahrenheit-Celsius table
for fahr = 0, 20, ..., 300 */
main()
{
int fahr, celsius;
int lower, upper, step;
lower = 0; /* lower limit of temperature scale */
upper = 300; /* upper limit */
step = 20; /* step size */
fahr = lower;
while (fahr <= upper)
 {
celsius = 5 * (fahr-32) / 9;
printf("%d\t%d\n", fahr, celsius);
fahr = fahr + step;
}
}
The two lines
/* print Fahrenheit-Celsius table
for fahr = 0, 20, ..., 300 */
are a comment, which in this case explains briefly what the program does. Any characters between /* and */ are ignored by the compiler; they may be used freely to make a program easier to understand. Comments may appear anywhere where a blank, tab or newline can.
In C, all variables must be declared before they are used, usually at the beginning of the function before any
executable statements. A declaration announces the properties of variables; it consists of a name and a list of
variables, such as
int fahr, celsius;
int lower, upper, step;
The type int means that the variables listed are integers; by contrast with float, which means floating point,
i.e., numbers that may have a fractional part. The range of both int and float depends on the machine you are
using; 16-bits ints, which lie between -32768 and +32767, are common, as are 32-bit ints. A float number is
typically a 32-bit quantity, with at least six significant digits and magnitude generally between about 10-38 and
1038.
C provides several other data types besides int and float, including:
char character - a single byte
short short integer
long long integer
double double-precision floating point
The size of these objects is also machine-dependent. There are also arrays, structures and unions of these basic
types, pointers to them, and functions that return them, all of which we will meet in due course.
Computation in the temperature conversion program begins with the assignment statements
lower = 0;
upper = 300;
step = 20;
which set the variables to their initial values. Individual statements are terminated by semicolons.
Each line of the table is computed the same way, so we use a loop that repeats once per output line; this is the purpose of the while loop
while (fahr <= upper)
{
...
}
The while loop operates as follows: The condition in parentheses is tested. If it is true (fahr is less than or equal to upper), the body of the loop (the three statements enclosed in braces) is executed. Then the condition is retested, and if true, the body is executed again. When the test becomes false (fahr exceeds upper) the loop ends, and execution continues at the statement that follows the loop. There are no further statements in this program, so it terminates.The body of a while can be one or more statements enclosed in braces, as in the temperature converter, or a single statement without braces, as in
while (i < j)
i = 2 * i;
In either case, we will always indent the statements controlled by the while by one tab stop (which we have
shown as four spaces) so you can see at a glance which statements are inside the loop. The indentation emphasizes the logical structure of the program. Although C compilers do not care about how a program looks, proper indentation and spacing are critical in making programs easy for people to read. We recommend writing only one statement per line, and using blanks around operators to clarify grouping. The position of braces is less important, although people hold passionate beliefs. We have chosen one of several popular styles. Pick a style that suits you, then use it consistently.Most of the work gets done in the body of the loop. The Celsius temperature is computed and assigned to the variable celsius by the statement
celsius = 5 * (fahr-32) / 9;
The reason for multiplying by 5 and dividing by 9 instead of just multiplying by 5/9 is that in C, as in many other languages, integer division truncates: any fractional part is discarded. Since 5 and 9 are integers. 5/9 would be truncated to zero and so all the Celsius temperatures would be reported as zero.
This example also shows a bit more of how printf works. printf is a general-purpose output formatting
function,  Its first argument is a string of characters to be printed,with each % indicating where one of the other (second, third, ...) arguments is to be substituted, and in what form it is to be printed. For instance, %d specifies an integer argument, so the statement
printf("%d\t%d\n", fahr, celsius);
causes the values of the two integers fahr and celsius to be printed, with a tab (\t) between them.
Each % construction in the first argument of printf is paired with the corresponding second argument, third
argument, etc.; they must match up properly by number and type, or you will get wrong answers.
By the way, printf is not part of the C language; there is no input or output defined in C itself. printf is just a
useful function from the standard library of functions that are normally accessible to C programs. The behaviour of printf is defined in the ANSI standard, however, so its properties should be the same with any compiler and library that conforms to the standard.In order to concentrate on C itself, . In particular, we will defer formatted input until then. If you have to input numbers. scanf is like printf, except that it reads input instead of writing output.There are a couple of problems with the temperature conversion program. The simpler one is that the output isn't very pretty because the numbers are not right-justified. That's easy to fix; if we augment each %d in the printf
statement with a width, the numbers printed will be right-justified in their fields. For instance, we might say
printf("%3d %6d\n", fahr, celsius);
to print the first number of each line in a field three digits wide, and the second in a field six digits wide, like this:
0 -17
20 -6
40 4
60 15
80 26
100 37
...
The more serious problem is that because we have used integer arithmetic, the Celsius temperatures are not very accurate; for instance, 0oF is actually about -17.8oC, not -17. To get more accurate answers, we should use floatingpoint arithmetic instead of integer. This requires some changes in the program. Here is the second version:
#include <stdio.h>
/* print Fahrenheit-Celsius table
for fahr = 0, 20, ..., 300; floating-point version */
main()
{
float fahr, celsius;
float lower, upper, step;
lower = 0; /* lower limit of temperatuire scale */
upper = 300; /* upper limit */
step = 20; /* step size */
fahr = lower;
while (fahr <= upper)
 {
celsius = (5.0/9.0) * (fahr-32.0);
printf("%3.0f %6.1f\n", fahr, celsius);
fahr = fahr + step;
}
}
This is much the same as before, except that fahr and celsius are declared to be float and the formula for
conversion is written in a more natural way. We were unable to use 5/9 in the previous version because integer division would truncate it to zero. A decimal point in a constant indicates that it is floating point, however, so 5.0/9.0 is not truncated because it is the ratio of two floating-point values.
If an arithmetic operator has integer operands, an integer operation is performed. If an arithmetic operator has one floating-point operand and one integer operand, however, the integer will be converted to floating point before the operation is done. If we had written (fahr-32), the 32 would be automatically converted to floating point.Nevertheless, writing floating-point constants with explicit decimal points even when they have integral values emphasizes their floating-point nature for human readers.. For now, notice that the assignment
fahr = lower;
and the test
while (fahr <= upper)
also work in the natural way - the int is converted to float before the operation is done.
The printf conversion specification %3.0f says that a floating-point number (here fahr) is to be printed at
least three characters wide, with no decimal point and no fraction digits. %6.1f describes another number
(celsius) that is to be printed at least six characters wide, with 1 digit after the decimal point. The output looks
like this:
0 -17.8
20 -6.7
40 4.4
...
Width and precision may be omitted from a specification: %6f says that the number is to be at least six characters wide; %.2f specifies two characters after the decimal point, but the width is not constrained; and %f merely says to print the number as floating point.

%d print as decimal integer
%6d print as decimal integer, at least 6 characters wide
%f print as floating point
%6f print as floating point, at least 6 characters wide
%.2f print as floating point, 2 characters after decimal point
%6.2f print as floating point, at least 6 wide and 2 after decimal point Among others, printf also recognizes %o for octal, %x for hexadecimal, %c for character, %s for character
string and %% for itself.

A C Tutorial Introduction

Let us begin with a quick introduction in C. Our aim is to show the essential elements of the language in real
programs, but without getting bogged down in details, rules, and exceptions. At this point, we are not trying to be
complete or even precise (save that the examples are meant to be correct). We want to get you as quickly as
possible to the point where you can write useful programs, and to do that we have to concentrate on the basics:
variables and constants, arithmetic, control flow, functions, and the rudiments of input and output. We are
intentionally leaving out of this chapter features of C that are important for writing bigger programs. These include
pointers, structures, most of C's rich set of operators, several control-flow statements, and the standard library.
This approach and its drawbacks. Most notable is that the complete story on any particular feature is not found
here, and the tutorial, by being brief, may also be misleading. And because the examples do not use the full power
of C, they are not as concise and elegant as they might be. We have tried to minimize these effects, but be warned.
Another drawback is that later chapters will necessarily repeat some of this chapter. We hope that the repetition
will help you more than it annoys.
In any case, experienced programmers should be able to extrapolate from the material in this chapter to their own
programming needs. Beginners should supplement it by writing small, similar programs of their own.

Getting Started:
The only way to learn a new programming language is by writing programs in it. The first program to write is the
same for all languages:
Print the words
hello, world
This is a big hurdle; to leap over it you have to be able to create the program text somewhere, compile it
successfully, load it, run it, and find out where your output went. With these mechanical details mastered,
everything else is comparatively easy.
In C, the program to print ``hello, world'' is
#include <stdio.h>
main()
{
printf("hello, world\n");
}
Just how to run this program depends on the system you are using. As a specific example, on the UNIX operating
system you must create the program in a file whose name ends in ``.c'', such as hello.c, then compile it with
the command
cc hello.c
If you haven't botched anything, such as omitting a character or misspelling something, the compilation will
proceed silently, and make an executable file called a.out. If you run a.out by typing the command
a.out
it will print
hello, world
On other systems, the rules will be different; check with a local expert.
Now, for some explanations about the program itself. A C program, whatever its size, consists of functions and
variables. A function contains statements that specify the computing operations to be done, and variables store
values used during the computation. C functions are like the subroutines and functions in Fortran or the procedures
and functions of Pascal. Our example is a function named main. Normally you are at liberty to give functions
whatever names you like, but ``main'' is special - your program begins executing at the beginning of main. This
means that every program must have a main somewhere.
main will usually call other functions to help perform its job, some that you wrote, and others from libraries that
are provided for you. The first line of the program,
#include <stdio.h>
tells the compiler to include information about the standard input/output library; the line appears at the beginning
of many C source files. The standard library is described in Chapter 7 and Appendix B.
One method of communicating data between functions is for the calling function to provide a list of values, called
arguments, to the function it calls. The parentheses after the function name surround the argument list. In this
example, main is defined to be a function that expects no arguments, which is indicated by the empty list ( ).
#include <stdio.h> include information about standard library
main() define a function called main
that received no argument values
{ statements of main are enclosed in braces
printf("hello, world\n"); main calls library function printf
to print this sequence of characters
}
 \n represents the newline character
The first C program
The statements of a function are enclosed in braces { }.
 The function main contains only one statement,
printf("hello, world\n");
A function is called by naming it, followed by a parenthesized list of arguments, so this calls the function printf
with the argument "hello, world\n". printf is a library function that prints output, in this case the string
of characters between the quotes.
A sequence of characters in double quotes, like "hello, world\n", is called a character string or string
constant. For the moment our only use of character strings will be as arguments for printf and other functions.
The sequence \n in the string is C notation for the newline character, which when printed advances the output to
the left margin on the next line. If you leave out the \n (a worthwhile experiment), you will find that there is no
line advance after the output is printed. You must use \n to include a newline character in the printf argument;
if you try something like
printf("hello, world");
the C compiler will produce an error message.
printf never supplies a newline character automatically, so several calls may be used to build up an output line
in stages. Our first program could just as well have been written
#include <stdio.h>
main()
{
printf("hello, ");
printf("world");
printf("\n");
}
to produce identical output.
Notice that \n represents only a single character. An escape sequence like \n provides a general and extensible
mechanism for representing hard-to-type or invisible characters. Among the others that C provides are \t for tab,
\b for backspace, \" for the double quote and \\ for the backslash itself.

A simple login program in C

This is a simple login program in C. While accepting password it masks each character using ‘*’ symbol and display the password in the next line after the user hits Enter key. It also accepts backspaces and acts accordingly.

#include<stdio.h>
#include<conio.h>

char pw[25],ch;
int i;
void main()
{
clrscr();
puts(“Enter password”);
while(1)
{
if(i<0)
i=0;
ch=getch();
if(ch==13)
break; /*13 is ASCII value of ENTER*/
if(ch==8) /*ASCII value of BACKSPACE*/
{
putch(‘b’);
putch(NULL);
putch(‘b’);
–i;
continue;
}
pw[i++]=ch;
ch=’*’;
putch(ch);
}
pw[i]=’?;
printf(“nn%s”,pw);
getch();
}

C program to convert a binary code to gray code

/*C program to convert a binary code to gray code - */ 
#include <stdio.h>
#include <math.h>

int bintogray(int);

int main ()
{
int bin, gray;

printf("Enter a binary number: ");
scanf("%d", &bin);
gray = bintogray(bin);
printf("The gray code of %d is %d\n", bin, gray);
return 0;
}

int bintogray(int bin)
{
int a, b, result = 0, i = 0;

while (bin != 0)
{
a = bin % 10;
bin = bin / 10;
b = bin % 10;
if ((a && !b) || (!a && b))
{
result = result + pow(10, i);
}
i++;
}
return result;
}

what is white-space in C programming ???

ans: white-space is the term used in c to describe blanks,tabs,newline,characters and comments. white-space separate one part of a statement from another and enables the compiler to identify where on element in a statement , such as int, ends and the next element begins. therefore, in the following statement :

 int age;

there must be at lest one white-space character ( usually a space) between int and age for the fruit .

compiler to be able to  distinguish them . on the  other hand , in the following statement :

= apple + oranges; // get the total fruit 

no white-space characters are necessary between fruit and  =, or between = and apple , although you are free to include some if you wish for readability purpose ..

Write a program in c for addition of two matrix

  

                           

                            

     //addition of given two matrixx

    #include<stdio.h>

    #include<conio.h>

    void main()

    {

    int a[3][3],b[3][3],c[3][3],i,j;

    clrscr();

    printf("\n\n\t\t\t-:enter no for the first matrix:-");

    for(i=0;i<3;i++)

     {

      for(j=0;j<3;j++)

       {

printf("\n\t ");

scanf("%d",&a[i][j]);

}

}

      printf("\n\t\t\t\t-:first matrix is:-\n\n\t\t\t\t\t");

      for(i=0;i<3;i++)

       {

for(j=0;j<3;j++)

  {

   printf("%d ",a[i][j]);

   }

   printf("\n\t\t\t\t\t");

   }

      printf("\n\t\t\t-:enter numbers for second matrix :-\n");

      for(i=0;i<3;i++)

       {

for(j=0;j<3;j++)

{

 printf("\n\t ");

 scanf("%d",&b[i][j]);

 }

 }

      printf("\t\t\t-:second matrix is:-\n\n\t\t\t\t");

      for(i=0;i<3;i++)

       {

for(j=0;j<3;j++)

  {

    printf("%d ",b[i][j]);

    }

    printf("\n\t\t\t\t");

    }

      printf("\n\n\t\t-:addition of given two matrixx is :-\n\n\t\t\t\t");

      for(i=0;i<3;i++)

       {

for(j=0;j<3;j++)

 {

  c[i][j]=a[i][j] + b[i][j];

  printf("%d ",c[i][j]);

  }

  printf("\n\t\t\t\t");

  }

  getch();

  }

WHAT IS AN IDENTIFIER IN "C" PROGRAMMING ??

    

• A c identifier is a name used to identify a variable , function , or many other  user-defined item . an identifier stars with a letter A to Z or a to z or an underscore _ followed by zero or more letters , underscores , digits ( 0 to 9) .