Question

Using the C Programming Language:

An integer number is said to be a perfect number if its factors, including 1 (but not the number itself), sum to the number. For example, 6 is a perfect number because 6 = 1 + 2 + 3. Write a function perfect that determines if parameter number is a perfect number. Use this function in a program that determines and prints all the perfect numbers between 1 and 1000. Print the factors of each perfect number to confirm that the number is indeed perfect.

Note that the function perfect should be a boolean function (returns a value of 'true' i.e. 1 or 'false' i.e. 0).

Example:

The perfect numbers between 1 and 1000 are:

6 is a perfect number; It's factors are = 1, 2, 3

Answer 1

ANSWER :

#include<stdio.h>

int test(int);
void printfactors(int);
int main(){
int number,i;
int perfect;
printf("Enter a number: ");
scanf("%d",&number);
do{
perfect=test(number);
if (perfect==1)
{
printf("\n%d ",number);
printfactors(number);
}
number++;
}while(number<1001);

printf("\nPress any key to quit ");
getch();
return 0;
}
int test(int NUM){
int result=0;
int larger=NUM, smaller=1;//saves the larger and smaller factor of NUM
int sum=0-NUM;// sum set to negative of NUM to not 'add' NUM to calculation

while(larger>smaller){
if(NUM%smaller==0){// if a factor, add both, the smaller and larger factor to sum
larger=NUM/smaller;
sum+=larger+smaller;
}
smaller++;//increment smaller factor by one
}

if(sum==NUM && NUM!=0){
result=1;
}

return result;
}

void printfactors(int number){
int i;
printf(" [ ");
for(i=1;i<=number;i++){
if(number%i==0){
printf("%d ",i);
}
}
puts("]");
return;
}

( OR )

ANOTHER ANSWER IS--------

#include <stdio.h>

void perfect(int num)

{

int i = 1;

int sum = 0;

while (i < num)

{

if (num % i == 0)

sum = sum + i;

i = i + 1;

}

i = 1;

if (sum == num)

{

printf ("%d = ", num);

while (i < num)

{

if (num % i == 0)

printf(" %d + ", i);

i = i + 1;

}

printf("\n%d is perfect number\n", num);

}

else

printf("%d is NOT perfect number\n", num);

}

int main()

{

int i = 2;

while (i < 1000)

{

perfect(i);

i = i + 1;

}

return 0;

}