Question

试图写一个程序，会发现从 1 到 N 的数字范围的阶乘，N 是找到阶乘的最终数字，我写了一个非递归程序。它只适用于整数 1 和 2 在循环中，我不知道如何解决它，因为逻辑似乎很好，我还是一个初学者，所以我知道我可能错过了一些明显的东西，但无论如何这里的代码：

 #include<stdio.h>
int main() {
    
    int firstnumber;
    int finalnumber;
printf("this is a program to calculate the factorial of numbers between 1 to N\n"); 
printf("please enter the final number : ");
 
scanf("%d",&finalnumber);
int i;
int factorial=1;
for (firstnumber=1;firstnumber<=finalnumber;firstnumber++) {
    printf("the factorial of %d is : ",firstnumber);
 
 
    for (i=1;i<=firstnumber;i++) {
        factorial=factorial*i;
    }
    printf("%d \n ",factorial);
}
return 0;
}

2

1

Answer 1

您需要在每次计算之前初始化factorial。

int i;
// delete this
//int factorial=1;
for (firstnumber=1;firstnumber<=finalnumber;firstnumber++) {
    printf("the factorial of %d is : ",firstnumber);
    // move the declaration here
    int factorial=1;
    for (i=1;i<=firstnumber;i++) {
        factorial=factorial*i;
    }
    printf("%d \n ",factorial);
}

Answer 2

您的两个循环是冗余的：您可以从number - 1的阶乘计算number的阶乘

这是只有一个循环的程序。复杂度 O（N）。

注意使用int会很快溢出。

#include<stdio.h>
int main() {
    
    int number;
    int finalnumber;
    printf("this is a program to calculate the factorial of numbers between 1 to N\n"); 
    printf("please enter the final number : ");
    scanf("%d",&finalnumber);
    int factorial = 1;
    for (number=1; number<=finalnumber; number++) {
        printf("the factorial of %d is : ",number);
        factorial *= number;
        printf("%d \n",factorial);
    }
    return 0;
}