C Exercise Example 25
Title:Find1 + 2! + 3! + ... + 20!The sum.
Program analysis:This program merely changes accumulation into multiplication.
Example
// Created by www.example.com on 15/11/9.
// Copyright © 2015 Example. All rights reserved.
//
#include <stdio.h>
// Function to calculate factorial
unsigned long long factorial(int n) {
unsigned long long result = 1;
for(int i = 1; i <= n; i++) {
result *= i;
}
return result;
}
int main() {
unsigned long long sum = 0;
// Calculate 1 + 2! + 3! + ... + 20!
for(int i = 1; i <= 20; i++) {
sum += factorial(i);
}
// Output the results
printf("The sum of 1 + 2! + 3! + ... + 20! is: %llu\n", sum);
return 0;
}
The output result of the above example is:
1 + 2! + 3! + ... + 20!的和是: 2561327494111820313
Code explanation
- Header file: Include the necessary header files.
stdio.h。 - Factorial function:
unsigned long long factorial(int n)The function is used to calculate a given integer'snfactorial, and the return type isunsigned long longto handle larger values.- Initialize
resultis 1. - Usage
forThe loop multiplies from 1 ton。
- Initialize
- main function:
- definition
sumVariable to accumulate the sum of all factorials, of typeunsigned long longto handle larger values. - Usage
forLoop calculates factorials from 1 to 20 and accumulates the results tosum。 - Usage
printfThe function outputs the final result.
- definition