History behind C language

How C language evolved?

Multics project started in 1964 cooperated with MIT ,  General Electric and Bell Labs but it was not very successful one. Multics had numerous features intended to result in high availability so that it would support a Computing utility similar to Telephone and Electricity services. It was not failing to deliver the promised fast and convenient on-line system,it was failing to deliver anything usable at all. They were trying to create an operating system that was much too big and to do it on hardware that was much too small. 

Bell Labs disenchanted in 1969 Multics and looked around for other tasks. When Bell Labs withdrew from the Multics research consortium,One researcher,Ken Thompson, was left with some Multics-inspired ideas about to build a file system. He was also left without a machine on which to play a game he had written called "Space Travel", a science-fiction simulation that involved navigating a rocket through the solar system. Ken Thompson was keen to work on another operating system and made several proposal to Bell Management but all declined. He didn't wait for official approval, He and his co-worker Dennis M. Ritchie amused themselves porting Thompson's "Space Travel" software to a little used PDP-7. Thompson worked intensively on providing the PDP-7 with the rudiments of a new operating system,much simpler and lighter than Multics. Everything was written in assembler language. Brian Kernighan coined the name "UNIX".

After a brief and unsuccessful filtration with Fortran,Thompson created a language B by simplifying the research language BCPL(Basic Combined Programming Language) so its interpreter would fit in the PDP-7's 8K word memory. B was never really successful; the hardware limits only provided room for an interpreter, not a compiler. The resulting slow performance prevented B from being used for system programming of UNIX itself. B simplified BCPL by omitting some features. Thompson conceived the ++ and -- operators(unary operator) and added them to the B compiler  on PDP-7. Typeless language proved to be unworkable when development switched in 1970 the newly introduced PDP-11. While at that time they were facing the problem for multiple datatypes and performance led Thompson to re-implement the OS in PDP-11 assembler rather than B. Dennis Ritchie capitalized on the more powerful PDP-11 to create "New B" which solved the both problems, multiple datatype and performance. "New B" in 1971- the name quickly evolved to "C" in 1972- was compiled rather than interpreted. 

Program to find strong number.

Strong Number: A strong number is a number in which the sum of factorial of all the digits of the given number is equal to the given number. E.g. 145=1!+4!+5!

#include<stdio.h>
#include<conio.h>
void main()
{
int i=0,n;
long double f=1;
clrscr();
printf("Enter the number : ");
scanf("%d",&n);

for(i=n;i>0;i=i/10)

{

r=i%10;

for(i=r;i>0;i--)
f=f*i;

s=s+f;

}

if(s==n)

printf("The number is strong.");

else

printf("The number is not strong number.");

getch();

}

Factorial using recursion

#include<stdio.h>
long int fact(long int);
int main()
{
long int n,k=1;
clrscr();
printf("Enter the number:");
scanf("%ld",&n);
k=fact(n);
printf("Factorial is: %ld",k);

getch();
return 0;
}
long int fact(long int n)
{
long int f=1;
if(n==0)
return 1;
else
f=n*fact(n-1);
return f;
}

Output: 
Enter the number: 10
Factorial is: 3628800

Program for Binary search in array.

#include<stdio.h>
int main()
{
int a[100],i,n,s,k;
clrscr();
printf("\nEnter the length of array:");
scanf("%d",&n);
printf("\n Enter distinct elements of array: ");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
printf("\nEnter the searching element: ");
scanf("%d",&s);
k=binary(a,s,n);
if(k!=-1)
printf("\n\nThe searching element is at %d",k+1);
else
printf("\n\nThe element is not found in the array");
return 0;
}
int binary(int a[],int p,int q)
{
int hi,low=0,mid;
hi=q-1;
while(low<=hi)
{
mid=(low+hi)/2;
if(p==a[mid])
return(mid);
if(p<a[mid])
hi=mid-1;
else
low=mid+1;
}
return(-1);
}

Output:
Enter the length of array: 20
Enter distinct element of array: 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Enter the searching element: 20
The searching element is at 20

Total number of Trailing zeros in the factorial of an integer

#include<stdio.h>
int main()

{
long int i,n;
int zero,j;
clrscr();
        printf("Enter the number:");
scanf("%ld",&n);
     zero=0;
for(j=5;j<n;j*=5)
{
zero+=n/j;
}
printf("\n%d",zero);

getch();
return 0;
}


Output:
Eneter the number : 25
5

Transpose of a square matrix

#include<stdio.h>
#define max 100
void main()
{
int a[max][max],i,j,n;
clrscr();
printf("Enter the size of matrix:");
scanf("%d",&n)
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
scanf("%d",&a[i][j]);
}
}
printf("\n\nOriginal matrix: \n\n");
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
printf(" %d ",a[i][j]);
}
printf("\n");
}
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
if(i<j)
{

a[i][j]=a[i][j]+a[j][i];
a[j][i]=a[i][j]-a[j][i];
a[i][j]=a[i][j]-a[j][i];
}

}
}
printf("\nTransposed matrix:\n");
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
printf(" %d ",a[i][j]);
}
printf("\n");
}
getch();
}