C Program for fibanacci series using recursion.

#include<stdio.h>
#include<conio.h>
int fib(int);
void main()
{
int a,b,i,c;
clrscr();
printf("Enter the N value");
scanf("%d",&a);
for(i=0;i<a;i++)
{
printf("\n%d",fib(i));
}
getch();
}
int fib(int x)
{
if(x==0)
return(0);
if(x<=1)
{
return(1);
}
else
{
return(fib(x-1)+(fib(x-2)));
}
}

C PROGRAM FOR PASCAL TRIANGLE.

#include<stdio.h>
#include<conio.h>
void main()
{
int i=1,j,num,x=1;
clrscr();
printf("Please Enter the Number :");
scanf("%d",&num);
printf("\n\n");
printf("OUTPUT:\n");
printf("------");
printf("\n\n");
printf("The Pascal triangle is\n");
printf("**********************\n");
for(i=1;i<=num;i++)
{
for(j=1;j<=i;j++)
{
if(j==1)
{
x=1;
printf("%d",x);
}
else
{
x=(x*(i-j+1)/(j-1));
printf("%d",x);
}
}
printf("\n");
}
getch();
}

C Program for Prime Number Generation.

#include<stdio.h>
#include<conio.h>
void main()
{
int n,j,a=0,i;
clrscr();
printf(" Please Enter a number :");
scanf("%d",&n);
printf("\n\n");
printf("OUTPUT:\n");
printf("------");
printf("\n\n");
printf("The Prime Number series is\n");
printf("**************************");
for(j=1;j<=n;j++)
{
for(i=2;i<j;i++)
{
if(j%i==0)
{
a=1;
goto x;
}
}
if((a==0)&&(j!=1))
{
printf("\n%d",j);
}
x:
a=0;
}
getch();
}

C Program For REPLACE OF STRING. 

#include<stdio.h>
#include<conio.h>
void main()
{
char a[100],b[100],c[100],d[100];
int i,j,k,l1,l2,l3,m,count=-1;
clrscr();
printf("\t\t\t REPLACE OF STRING ");
printf("\n\t\t\t ********************");
printf("\n\n\tINPUT");
printf("\n\t*******");
printf("\n\nEnter the first String:");
scanf("%[a-z ]s",a);
printf("\nEnter the substring:");
scanf("%s",b);
printf("\nEnter the replace string:");
scanf("%s",c);
printf("\n\n\tOUTPUT");
printf("\n\t*******");
for(i=0;a[i]!='\0';i++)
l1=i;
for(i=0;b[i]!='\0';i++)
l2=i;
for(i=0;c[i]!='\0';i++)
l3=i;
for(i=0;a[i]!='\0';i++)
d[i]=a[i];
d[i]='\0';
if(l1>=l2)
{
do
{
for(i=0,j=0;a[i]!='\0' && b[j]!='\0';i++ )
{
if(a[i]==b[j])
{
count++;
j++;
}
else
{
count=-1;
if(j>0)
i--;
j=0;
}
}
m=i;
if(count==l2)
{
i=i-j;
for(k=0;c[k]!='\0';i++,k++)
a[i]=c[k];
if(l2!=l3)
{
for( ;d[m]!='\0';m++,i++)
{
a[i]=d[m];
}
}
//a[i]='\0';
//printf("\nReplaced string:%s",a);
}
else
break;
//printf("\nThe substring is not there");
}while(a[i]!='\0');
printf("\nReplaced string:%s",a);
}
getch();
}

C Program for String Length.

#include<stdio.h>
#include<conio.h>
void main()
{
int i,c=0;
char a[50];
clrscr();
printf("OUTPUT\n");
printf("------");
printf("\n\n");
printf("Please Enter a String:\n");
printf("*********************");
scanf("%s",a);
for(i=0;a[i]!='\0';i++)
{
c=c+1;
}
printf("\n\n");
printf("Length Of The Given String is=%d\n",c);
printf("*****************************");
getch();
}

C Program For REPLACE OF STRING.

#include<stdio.h>
#include<conio.h>
void main()
{
char a[100],b[100],c[100],d[100];
int i,j,k,l1,l2,l3,m,count=-1;
clrscr();
printf("\t\t\t REPLACE OF STRING ");
printf("\n\t\t\t ********************");
printf("\n\n\tINPUT");
printf("\n\t*******");
printf("\n\nEnter the first String:");
scanf("%[a-z ]s",a);
printf("\nEnter the substring:");
scanf("%s",b);
printf("\nEnter the replace string:");
scanf("%s",c);
printf("\n\n\tOUTPUT");
printf("\n\t*******");
for(i=0;a[i]!='\0';i++)
l1=i;
for(i=0;b[i]!='\0';i++)
l2=i;
for(i=0;c[i]!='\0';i++)
l3=i;
for(i=0;a[i]!='\0';i++)
d[i]=a[i];
d[i]='\0';
if(l1>=l2)
{
do
{
for(i=0,j=0;a[i]!='\0' && b[j]!='\0';i++ )
{
if(a[i]==b[j])
{
count++;
j++;
}
else
{
count=-1;
if(j>0)
i--;
j=0;
}
}
m=i;
if(count==l2)
{
i=i-j;
for(k=0;c[k]!='\0';i++,k++)
a[i]=c[k];
if(l2!=l3)
{
for( ;d[m]!='\0';m++,i++)
{
a[i]=d[m];
}
}
//a[i]='\0';
//printf("\nReplaced string:%s",a);
}
else
break;
//printf("\nThe substring is not there");
}while(a[i]!='\0');
printf("\nReplaced string:%s",a);
}
getch();
}