c-CS50凯撒.大写字母后打印的不可见字符

Question

我已经在CS50中为Caesar项目编写了下面的代码，我觉得它达到了目的，但当我运行检查时，两个包含大写字母的检查都不正确。每个大写字母之间似乎打印了一些额外的字符，而这些字符在我自己运行代码时没有出现。我的代码中是否遗漏了导致这种情况发生的内容？

来自Check50 的消息

:( encrypts "BARFOO" as "EDUIRR" using 3 as key
expected "ciphertext: ED...", not "ciphertext: E..."
:( encrypts "BaRFoo" as "FeVJss" using 4 as key
expected "ciphertext: Fe...", not "ciphertext: F..."

我的代码

#include <cs50.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>

bool only_digits(string s);
char rotate(int, int);
int main(int argc, string argv[])
{
//make sure key is entered correctly
{
if (argc != 2)
{
printf("Usage: ./caesar keyn");
return 1;
}
else
{
int cont = only_digits(argv[1]);
if (cont != 1)
{
return 1;
}
else
{
// convert key from string to int
int key = atoi(argv[1]);
string plain = get_string("plain text: n");
// rotate the letters using the key
printf("ciphertext: ");
{
for (int i = 0, len = strlen(plain); i < len; i++)
{
rotate(plain[i], key);
}
}
printf("n");
}
}
}
}
//rotate the letters using the key
char rotate(int p, int i)
{
// rotate uppers
if isupper(p)
{
p = p - 65;
char c = (p + i) % 26;
c += 65;
printf("%c", c);
}
// rotate lowers
if islower(p)
{
p = p - 97;
char c = (p + i) % 26;
c += 97;
printf("%c", c);
}
// if its a character keep the same
else
{
printf("%c", p);
}
return 0;
}
//make sure key entered is only digits
bool only_digits(string s)
{
for (int i = 0, len = strlen(s); i < len; i++)
{
if (!isdigit(s[i]))
{
printf("Usage: ./caesar keyn");
return 0;
}
else
{
;
}
}
return 1;
}

Answer 1

虽然我不确定这是否是您唯一的错误，但您在rotate函数中忘记了一个else if，因此大写字母将以第一种大小写打印，但在修改后也将else打印为第二种大小写。

char rotate(int p, int i)
{
// rotate uppers
if isupper(p)
{
p = p - 65;
char c = (p + i) % 26;
c += 65;
printf("%c", c);
}
// rotate lowers
else if islower(p) // without else if here, upper cases would fall into the else below with p - 65
{
p = p - 97;
char c = (p + i) % 26;
c += 97;
printf("%c", c);
}
// if its a character keep the same
else
{
printf("%c", p);
}
return 0;
}