英文:
Why does it tell me its an Armstrong number when I enter strings?
问题
这是用于查找一个三位数的阿姆斯特朗数的代码。但是，当我输入字符串或任何其他特殊字符时，它会将其分类为阿姆斯特朗数，而实际上应该相反。
#include <stdio.h>
#include <stdlib.h>
int main() {
int a, original, rev, rem;
printf("输入数字：\n");
scanf("%d", &a);
original = a;
rev = 0;
while (a != 0) {
rem = a % 10;
rev = rev + (rem * rem * rem);
a /= 10;
}
if (rev == original) {
printf("这是一个阿姆斯特朗数\n");
} else {
printf("这不是一个阿姆斯特朗数\n");
}
}
英文:
This is the code for finding an Armstrong number of 3 digits. But when i enter strings or any other special character it categorizes it as an armstrong number while it should be other way around.
#include <stdio.h>
#include <stdlib.h>
int main() {
int a, original, rev, rem;
printf("Enter the number : \n");
scanf("%d", & a);
original = a;
rev = 0;
while (a != 0) {
rem = a % 10;
rev = rev + (rem * rem * rem);
a /= 10;
}
if (rev == original) {
printf("Its an Armstrong number\n");
} else {
printf("Its not an Armstrong number \n");
}
}
答案1
得分: 3
这是未定义行为，因为您使用了未初始化的变量 a。
您应该检查不正确的输入：
if (scanf("%d", &a) != 1)
{
printf("无效的输入\n");
return 1;
}
英文:
It is Undefined Behaviour as you use not initialized variable a.
You should have checked for the incorrect input:
if(scanf("%d", &a) != 1)
{
printf("Invalid input\n");
return 1;
}
答案2
得分: 3
你需要检查 scanf 的结果 - 它将返回成功转换和分配的项目数量。
if (scanf("%d", &a) != 1)
// 输入错误
else
// 检查 a 是否是阿姆斯特朗数
像 `nnnniii` 这样的输入不是有效的整数，所以读取失败，`a` *不会被更新*。
虽然 `auto` 变量的初始值是*不确定的*，但 `a` 可能具有初始值 `0`，所以你的测试会偶然通过。
英文:
You need to check the result of scanf - it will return the number of items successfully converted and assigned.
if ( scanf( "%d", &a ) != 1 )
// bad input
else
// check if a is an armstrong #
An input like nnnniii is not a valid integer, so the read fails and a is not updated.
While the initial value of auto variables is indeterminate, it's possible that a has an initial value of 0, so your test passes by accident.
答案3
得分: 1
#include <stdio.h>
#include <stdlib.h>
int main() {
int a, original, rev, rem;
printf("Enter the number : \n");
if(scanf("%d", &a) != 1)
{
printf("This is not a number\n");
return 1;
}
original = a;
rev = 0;
while (a != 0) {
rem = a % 10;
rev = rev + (rem * rem * rem);
a /= 10;
}
if (rev == original) {
printf("It's an Armstrong number\n");
} else {
printf("It's not an Armstrong number\n");
}
}
When you get a value, you need to check if it is a number or not.
英文:
#include <stdio.h>
#include <stdlib.h>
int main() {
int a, original, rev, rem;
printf("Enter the number : \n");
if(scanf("%d", &a) != 1)
{
printf("This is not number\n");
return 1;
}
original = a;
rev = 0;
while (a != 0) {
rem = a % 10;
rev = rev + (rem * rem * rem);
a /= 10;
}
if (rev == original) {
printf("Its an Armstrong number\n");
} else {
printf("Its not an Armstrong number \n");
}
}
When you get value, you need to check it is number or not.
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