C语言 如何理解c中的模数
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How to make sense of modulo in c
提问by Cy Bu
i am not understanding this modulo in c languge.
For example:
我不理解 c 语言中的这个模数。
例如：
#include <stdio.h>
#include<math.h>
int main()
{
int my_input[] = {23, 22, 21, 20, 19, 18};
int n, mod;
int nbr_items = sizeof(my_input) / sizeof(my_input[0]);
for (n = 0; n < nbr_items; n++)
{
mod = my_input[n] % 4;
printf("%d modulo %d --> %d\n", my_input[n], 4, mod);
}
}
Gives:
给出：
23 modulo 4 --> 3
22 modulo 4 --> 2
21 modulo 4 --> 1
20 modulo 4 --> 0
19 modulo 4 --> 3
18 modulo 4 --> 2
I would have expected a number that i can make sense of.
Essentially i am trying to test if a number is divisible by 4.
我会期望一个我能理解的数字。
本质上，我试图测试一个数字是否可以被 4 整除。
回答by rakeshb
The modulo operator in C will give the remainder that is left over when one number is divided by another. For example, 23 % 4 will result in 3 since 23 is not evenly divisible by 4, and a remainder of 3 is left over.
C 中的模运算符将给出一个数除以另一个数时剩下的余数。例如，23 % 4 将导致 3，因为 23 不能被 4 整除，并且剩下 3 的余数。
If you want to output whether or not a number is divisible by 4, you need to output something other than just the mod result. Essentially, if mod = 0 than you know that one number is divisible by another.
如果你想输出一个数是否能被 4 整除，你需要输出一些不仅仅是 mod 结果的东西。本质上，如果 mod = 0，那么您就知道一个数可以被另一个数整除。
If you want to output whether or not the number is divisible by 4, I would suggest creating a new character that is set to "y" (yes) or "n" (no) depending on the result of the mod operation. Below is one possible implementation to generate a more meaningful output:
如果要输出数字是否可以被 4 整除，我建议创建一个新字符，根据 mod 操作的结果设置为“y”（是）或“n”（否）。以下是生成更有意义的输出的一种可能实现：
#include <stdio.h>
#include <ctype.h>
#include <math.h>
int main()
{
int my_input[] = {23, 22, 21, 20, 19, 18};
int n, mod;
char is_divisible;
int nbr_items = sizeof(my_input) / sizeof(my_input[0]);
for (n = 0; n < nbr_items; n++)
{
mod = my_input[n] % 4;
is_divisible = "y" ? mod == 0 : "n";
printf("%d modulo %d --> %c\n", my_input[n], 4, is_divisible);
}
}
This will give the following:
这将给出以下内容：
23 modulo 4 --> n
22 modulo 4 --> n
21 modulo 4 --> n
20 modulo 4 --> y
19 modulo 4 --> n
18 modulo 4 --> n
回答by paratrooper
I'm sure we know the basic division equation from high school math
我相信我们知道高中数学中的基本除法方程
dividend = divisor*quotient + remainder
股息=除数*商+余数
Now:
1. The "/" operator gives us the quotient.
2. The "%" operator gives us the remainder
现在：
1. "/" 运算符给我们商。
2. "%" 运算符给我们余数
example:
例子：
say a = 23, b = 4
a / b = 23 / 4 = 5
a % b = 23 % 4 = 3
23 = 4*5 + 3
Here 4 is the quotient and 3 is the remainder.
这里4是商，3是余数。
If a number is perfectly divisible by a divisor, then remainder is zero.
如果一个数能被一个除数完全整除，则余数为零。
So:
所以：
20/4 = 5 (quotient)
20%4 = 0 (remainder)
To test if a no if divisible by 4, the check should be something like if (num % 4 == 0).
Hope this helps!
要测试是否可以被 4 整除，检查应该类似于if (num % 4 == 0)。
希望这可以帮助！
