{"id":691,"date":"2024-10-19T13:19:11","date_gmt":"2024-10-19T07:49:11","guid":{"rendered":"https:\/\/codexplained.in\/?p=691"},"modified":"2025-11-24T15:40:49","modified_gmt":"2025-11-24T10:10:49","slug":"check-perfect-number","status":"publish","type":"post","link":"https:\/\/codexplained.in\/?p=691","title":{"rendered":"Check Perfect Number"},"content":{"rendered":"
\n#include <stdio.h>\n\n\/\/ Function to check if a number is perfect\nint isPerfect(int num) {\n    int sum = 0; \/\/ Initialize sum of divisors\n\n    \/\/ Loop to find divisors and sum them\n    for (int i = 1; i <= num \/ 2; i++) { \/\/ Only need to check up to num\/2\n        if (num % i == 0) { \/\/ Check if i is a divisor\n            sum += i; \/\/ Add divisor to sum\n        }\n    }\n\n    \/\/ Check if sum of divisors equals the number\n    return sum == num; \/\/ Return 1 (true) if perfect, else 0 (false)\n}\n\nint main() {\n    int number;\n\n    \/\/ Prompt user for input\n    printf("Enter a positive integer: ");\n    scanf("%d", &number);\n\n    \/\/ Check for valid input\n    if (number <= 0) {\n        printf("Please enter a positive integer.\\n");\n    } else {\n        \/\/ Check and display if the number is perfect\n        if (isPerfect(number)) {\n            printf("%d is a perfect number.\\n", number);\n        } else {\n            printf("%d is not a perfect number.\\n", number);\n        }\n    }\n\n    return 0;\n}\n\n<\/pre><\/div>\n\n\n
Explanation of the Code<\/h2>\n\n\n\n
Calls the is Perfect<\/code> function and displays the result.<\/p>\n\n\n\n
Header Files<\/strong>: We include stdio.h<\/code> to use standard input and output functions.<\/p>\n\n\n\n
Function isPerfect(int num)<\/code><\/strong>:<\/p>\n\n\n\n
Initializes a variable sum<\/code> to keep track of the sum of divisors.<\/p>\n\n\n\n
Uses a loop to find divisors from 1<\/code> to num \/ 2<\/code> (since a number cannot be divisible by a number larger than half of itself).<\/p>\n\n\n\n
If i<\/code> is a divisor (i.e., num % i == 0<\/code>), it adds i<\/code> to sum<\/code>.<\/p>\n\n\n\n
Finally, it checks if the sum<\/code> equals the original number, returning 1<\/code> if true (perfect) or 0<\/code> if false (not perfect).<\/p>\n\n\n\n
Main Function<\/strong>:<\/p>\n\n\n\n
Prompts the user to enter a positive integer.<\/p>\n\n\n\n
Checks if the input is valid (greater than 0).<\/p>\n\n\n\n
Output<\/h2>\n\n\n\n
Enter a positive integer: 6\n6 is a perfect number.\n\nEnter a positive integer: 10\n10 is not a perfect number.\n\nEnter a positive integer: -5\nPlease enter a positive integer.<\/code><\/pre>\n