Sum of 1s in binary of a denary number

Print in ascending & descending recursive.c

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+#include<stdio.h>
+/*Write a program that takes n numbers from the user and sort them in ascending order using a
+function. Then ask the user whether to print in ascending order or descending order. Write a
+recursive function for the print in both cases.*/
+int main(){
+	int len,x,i,j;
+	printf("Enter Length of array: ");
+	scanf("%d",&len);
+	int arr[len];
+	for(i=1;i<=len;i++){
+		printf("Element %d: ",i);
+		scanf("%d",&x);
+		arr[i]=x;
+	}
+	sort(len,arr);
+	printf("\nAscending:  ");
+	printAsc(1,len,arr);
+	printf("\nDescending:  ");
+	printDec(1,len,arr);
+}
+int sort(int a,int arr[a]){
+	int i,j,temp;
+	for(i=1;i<=a-1;i++){
+		for(j=i+1;j<=a;j++){
+		if(arr[i]>arr[j]){
+			temp=arr[i];
+			arr[i]=arr[j];
+			arr[j]=temp;
+		}
+
+	}
+}
+
+}
+int printAsc(int start, int end, int arr[]){
+	if(start==end+1)
+	return 0;
+	else{
+		printf("\nElement %d: %d",start,arr[start]);
+		printAsc(start+1,end,arr);
+	}
+}
+int printDec(int start,int end, int arr[]){
+	if(end==start-1)
+	return 0;
+	else{
+		printf("\nElement %d: %d",end,arr[end]);
+		printDec(start,end-1,arr);
+	}
+}
+

Sum of 1s in binary.c

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+#include<stdio.h>
+
+//Sum of 1s in binary of a denary number through a recursive function
+
+int sum(int x){
+	if (x==0) return 0;
+	else {
+		int count=0;
+		//count+=10;
+	return x%2+sum(x/2);
+	}
+}
+int main(){
+	int x;
+	printf("Enter a denary number: ");
+	scanf("%d",&x);
+	printf("sum is: %d",sum(x));
+}

sum of the digits.c

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+#include<stdio.h>
+
+//Recursive function which takes an integer as a parameter and returns the sum of the digits of the number
+
+int sum(int x){
+	if (x==0) return 0;
+	else {
+	return x%10+sum(x/10);
+	}
+}
+int main(){
+	int x;
+	printf("Enter a number: ");
+	scanf("%d",&x);
+	printf("Sum is: %d",sum(x));
+}
+