C program to reverse an array

C program to reverse an array

Here the program is given after running on the computer. The program given here is explained in a very easy way for you to understand.

Example of reverse an array,

INPUT: 10 20 30 40 50 60

OUTPUT: 60 50 40 30 20 10

Program:

#include <stdio.h>

#include <conio.h>

void main ()

{

int a[20] , temp[20], I, j, n;

clrscr ();

printf (“ Enter the number of elements in array - - - -“);

scanf (“%d”, &n);

printf (“ - - - - Enter %d numbers separated by space - - - -\n”, n );

for (i=0; i<n; i++)

{

scanf (“ %d”, &a[i]);

}

for (i=n-1, j=0; i>=0; i--, j++)

temp[j] = a[i];

for 9i=0; i<n; i++)

a[i] = temp[i];

printf (“Numbers in reverse order are - - - - \n”);

for 9i=0; i<n; i++)

printf (“%d\t”, a[i]);

getch ();

}

OUTPUT

Enter how many numbers (<=50) - - - - 6

- - - - Enter 6 numbers separated by space - - - -

10 20 30 40 50 60

Numbers in reverse order are - - - -

60    50    40    30    20    10

Explanation :

In this program, we first enter n numbers, where n is entered by the user. For this, we use a for loop to enter the value of n different numbers. Then to print their values in reverse order, we take a for loop for (i=n-1, j=0; i>=0; i--, j++) to copy element into array temp string from end of array a. We then take another for loop to copy the reversed array back to the original array.

Here is some another programs of array that all programmer should know.

Program:

C program to enter the value of five numbers and then print their values.

#include <stdio.h>

#include <conio.h>

void main ()

{

int i, a[5];

clrscr ();

printf (“Enter 5 numbers - - - - -\n”);

for (i=0; i<5; i++)

{

printf (“Enter number a[%d] :”, i);

scanf (“%d”, &a[i]);

}

printf (“Numbers entered are - - - - -“);

for (i=0; i<5; i++)

printf (“\n\tElement a[%d] is : %d”, i, a[i] );

getch ();

}

OUTPUT

Enter 5 numbers - - - - -

Enter number a[0] : 10

Enter number a[1] : 20

Enter number a[2] : 30

Enter number a[3] : 40

Enter number a[4] : 50

Numbers entered are - - - - -

Enter number a[0] : 10

Enter number a[1] : 20

Enter number a[2] : 30

Enter number a[3] : 40

Enter number a[4] : 50

Explanation:

 In this program, we enter five numbers and print their values. For this , we need to process each element. Processing each element is known as traversing an array. This can simply be done by using a for loop or any other looping statement. In this program, taking for loop, we enter the values of 5 different numbers and then print out their values using printf statement. The number of passes through the loop will therefore equal to number of array elements to be processed.

A program to print the number of days from start of year to specified date (for non- leap year)

#include <stdio.h>

#include <conio.h>

void main ()

{

int I;

int month, day, t_day;

int d_per_mo[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

clrscr ();

printf (“Enter month (1 to 12) :”);

scanf (“Enter day 91 to 31):”);

scanf (“%d”, &day);

t_day = day;

for (i=0; i<month-1; i++)

t_day += d_per_mo[i];

printf (“Total days passed in year till %d/%d = %d”, day, month, t_day);

getch ();

}

OUTPUT
Enter month (1 to 12) : 4

Enter day ( 1 to 31): 22

Total days passed in year till 22/4 = 112

Explanation:

Suppose we enter month = 4 and day = 22 then t_day = 112

for     i=0;    t_day = 22+d_per_month[0]=22+31=53

for     i=1;    t_day = 53+d_per_month[1]=53+28=81

for     i=2;    t_day = 81+d_per_month[2]=81+31=112

for     i=3;    month – 1 = 3 so 3<3 is false and we exit the loop.