Updated C with 4 new prgms

C/Bin_To_Dec.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <conio.h>
+void main()
+{
+    // declaration of variables
+    int num, binary_num, decimal_num = 0, base = 1, rem;
+    printf(" Enter a binary number with the combination of 0s and 1s \n");
+    scanf(" %d", &num); // accept the binary number (0s and 1s)
+
+    binary_num = num; // assign the binary number to the binary_num variable
+
+    while (num > 0)
+    {
+        rem = num % 10; /* divide the binary number by 10 and store the remainder in rem variable. */
+        decimal_num = decimal_num + rem * base;
+        num = num / 10; // divide the number with quotient
+        base = base * 2;
+    }
+
+    printf(" The binary number is %d \t", binary_num);      // print the binary number
+    printf(" \n The decimal number is %d \t", decimal_num); // print the decimal
+    getch();
+}

C/Dec_To_Bin.c

@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <stdlib.h>
+int main()
+{
+    int a[10], n, i;
+    system("cls");
+    printf("Enter the number to convert: ");
+    scanf("%d", &n);
+    for (i = 0; n > 0; i++)
+    {
+        a[i] = n % 2;
+        n = n / 2;
+    }
+    printf("\nBinary of Given Number is=");
+    for (i = i - 1; i >= 0; i--)
+    {
+        printf("%d", a[i]);
+    }
+    return 0;
+}

C/Duck_Number.c

@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main()
+{
+    int dno, dkno, r, flg;
+    flg = 0;
+    printf("\n\n Check whether a number is a Duck Number or not: \n");
+    printf(" Input a number: ");
+    scanf("%d", &dkno);
+    dno = dkno;
+    while (dkno > 0)
+    {
+        if (dkno % 10 == 0)
+        {
+            flg = 1;
+            break;
+        }
+        dkno /= 10;
+    }
+    if (dno > 0 && flg == 1)
+    {
+        printf(" The given number is a Duck Number.\n");
+    }
+    else
+    {
+        printf(" The given number is not a Duck Number.\n");
+    }
+}

C/Leap_Year.c

@@ -0,0 +1,35 @@
+#include <stdio.h>
+int main()
+
+{
+    int year;
+    printf("Enter a year: ");
+    scanf("%d", &year);
+
+    // leap year if perfectly divisible by 400
+    if (year % 400 == 0)
+    {
+        printf("%d is a leap year.", year);
+    }
+
+    // not a leap year if divisible by 100
+    // but not divisible by 400
+    else if (year % 100 == 0)
+
+    {
+        printf("%d is not a leap year.", year);
+    }
+    // leap year if not divisible by 100
+    // but divisible by 4
+    else if (year % 4 == 0)
+    {
+        printf("%d is a leap year.", year);
+    }
+    // all other years are not leap years
+    else
+    {
+        printf("%d is not a leap year.", year);
+    }
+
+    return 0;
+}