#hacktoberfest | C

contribution/jowinjohnchemban/checkifsumofprime.c

@@ -0,0 +1,77 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<conio.h>
+#include<windows.h> //WINDOWS
+
+
+int checkPrime(int n);
+
+int main()
+{
+    int n, i, flag = 0;
+
+    system("CLS");
+    printf("\n\n\n");
+	printf("\n\t ######################################");
+	printf("\n\t #                                    #");
+	printf("\n\t #           CHECK A NUMBER           #");
+	printf("\n\t #           REPRESENTED AS           #");
+	printf("\n\t #      SUM OF TWO PRIME NUMBERS      #");
+	printf("\n\t #                                    #");
+	printf("\n\t ######################################\n");
+
+    Sleep(2000);
+    system("CLS");
+
+	printf("\n Enter a positive integer : ");
+    scanf("%d", &n);
+	printf("\n");
+
+
+    for(i = 2; i <= n/2 && !kbhit() ; ++i)
+    // iterate till i=n/2 and there is no key pressed - interupt
+    {
+        // condition for i to be a prime number
+        if (checkPrime(i) == 1)
+        {
+            // condition for n-i to be a prime number
+            if (checkPrime(n-i) == 1)
+            {
+                // n = primeNumber1 + primeNumber2
+                printf("  %d = %d + %d\n", n, i, n - i);
+                flag = 1;
+            }
+
+        }
+    }
+
+	printf("\a");
+    if (flag == 0)
+        printf(" %d cannot be expressed as the sum of two prime numbers.\a", n);
+        // cannot expressed as sum of two prime numbers
+
+
+	getch();
+	system("CLS");
+	return 0;
+	// EXIT
+}
+
+// Function to check prime number
+int checkPrime(int n)
+{
+    int i, isPrime = 1;
+
+    for(i = 2; i <= n/2; ++i)
+    {
+        if(n % i == 0)
+        {
+            isPrime = 0;
+            break;
+        }
+    }
+
+    return isPrime;
+}
+
+

contribution/jowinjohnchemban/prime.c

@@ -0,0 +1,24 @@
+ #include<stdio.h>
+
+int main(){
+
+    int num,i,count,n;
+    printf("Enter max range: ");
+    scanf("%d",&n);
+
+    for(num = 1;num<=n;num++){
+
+         count = 0;
+
+         for(i=2;i<=num/2;i++){
+             if(num%i==0){
+                 count++;
+                 break;
+             }
+        }
+
+         if(count==0 && num!= 1)
+             printf("%d,",num);
+    }
+   return 0;
+}