Important Program of C language in O level exam january 2019

Important Program of C language in O level exam january 2019

Write a function which accepts an array of size n containing integer values and returns average of all values. Call the function from main program.

#include<stdio.h>

#include<conio.h>

int avg(int[],int);

void main()

{

     int ar[5],i;

     clrscr();

     for(i=0;i<5;i++)

     {

          printf("Enter %d number

>> ",i+1);

          scanf("%d",&ar[i]);

     }

     printf("\n\tAverage = %d",avg(ar,5));

     getch();

}

int avg(int ar[],int s)

{

     int i=0,sum=0;

     for(i=0;i<s;i++)

          sum+=ar[i];

     return(sum/s);;

}

Write a function to display the multiplication table of the number.

#include<stdio.h>

void table(int);

void main()

{

     int i;

     printf("Enter number>> ");

     scanf("%d",&i);

     table(i);

    

}

void table(int n)

{

     int i;

     for(i=1;i<=10;i++)

          printf("\n%d*%d=%d",n,i,n*i);

}

Write a program to determine the sum of the following series:
    S = 1 – 3 + 5 – 7 + ...(n terms)

#include<stdio.h>

main()
{
    int n, s=0,i,sign=1;
    printf("\nEnter value of n=");
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        s=s+sign*(2*i-1);    
        sign=sign*(-1);
    }
    printf("\nThe sum of the series=%d",s);
}

Write a program to copy a file into another file.

#include <stdio.h> main() {     FILE *fp1, *fp2;     char ch;     fp1 = fopen("abc.txt", "r");     fp2 = fopen("xyz.txt", "w");     while((ch = getc(fp1)) != EOF)         putc(ch, fp2);     fclose(fp1);     fclose(fp2);     getch(); }

Write a program to display all the prime numbers between two positive integers m and n. The values of m and n are to be taken from the user.

Solution : 

#include<stdio.h>

void main()

{

     int n,m,p;

     printf("Enter range starting number>> ");

     scanf("%d",&m);

     printf("Enter range ending number>> ");

     scanf("%d",&n);

     if(m>n)

           printf("\n\tRange start should be less than range end");

     else

     {

           while(m<=n)

           {

                p=2;

                while(p<m)

                {

                      if(m%p==0)

                           break;

                      p++;

                }

                if(p==m)

                      printf("\t%d",p);

                m++;

           }

     }

}

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