这是我的Vigenere密码。我尝试使用do while循环重复迭代用户输入的密钥。密钥应用于用户输入的明文字，一次一个字母。我需要能够迭代密钥直到明文单词的结尾，以防密钥短于单词。我尝试使用do-while循环添加重复，第一个for循环是关键迭代。
＆＃39;＆＃39;的最后一行。循环是抛出未声明的标识符i的错误。这是我唯一的错误。内部＆＃39; for＆＃39;循环来自Caesar Cipher并通过所有检查。我认为我的while循环是错误的。如果我添加char * word [i]或word [i]的定义，无论我把它放在哪里，都会出现一个黯然失色的错误。我想使用这段代码而不是完全改变它，所以我理解是否可以这样做。不过，任何建议都会受到欢迎。
int main(int argc, char* argv[])
{
if (argc<2) //key
{
printf("Please enter your word key"); //prompts if no key is entered
return 1;
}
char* key = (argv[1]);
if(argc>=2)
{
printf("plaintext:");
char* word = GetString();
printf("ciphertext:");
do
{ //starts loop to repeat following for loop
for(int l=0; l<strlen(key); l++) //iterate over letters in key
{
int num=l;
for(int i=0; i<strlen(word); i++) //iterates through word entered by user as plaintext
{
if(isupper(word[i])) //if original characters are uppercase
{
int cipher = (word[i] + num -65) % 26 + 65;
printf("%c", cipher);
}
else if(islower(word[i])) //if original characters are lowercase
{
int cipher = (word[i] + num - 97) % 26 + 97;
printf("%c", (cipher));
}
else //all other types of characters
{
printf("%c", word[i]);
}
}
}
printf("\n");
}while((word[i])<strlen(word)); // loop to recommence iterating over letters in the key (i throwing undeclared identifier error)
}
}
答案 0 :(得分：1)
我认为你有太多的循环[等级]。
如果密钥长度在单词结束前用完，则重新开始加密单词开头中的单词（即错误）。
主要推动力是遍历所有单词字符。一个单循环使i递增，提供它也会增加l [模数密钥长度]。
这是一个清理过的版本[请原谅无偿的风格清理]：
#include <stdio.h>
#include <string.h>
#include <ctype.h>
// NOTE: I don't have GetString on my system
char *FakeGetString(void);
int
main(int argc, char *argv[])
{
// key
// prompts if no key is entered
if (argc < 2) {
printf("Please enter your word key");
return 1;
}
char *key = (argv[1]);
int klen = strlen(key);
if (argc >= 2) {
printf("plaintext:");
#if 0
char *word = GetString();
#else
char *word = FakeGetString();
#endif
int wlen = strlen(word);
printf("ciphertext:");
// current key index
int l = 0;
// starts loop to repeat following for loop
// iterates through word entered by user as plaintext
// advance to next key char [with wrap to beginning if we're short]
for (int i = 0; i < wlen; ++i, l = (l + 1) % klen) {
int num = key[l];
int cipher;
// if original characters are uppercase
if (isupper(word[i])) {
cipher = (word[i] + num - 65) % 26 + 65;
}
// if original characters are lowercase
else if (islower(word[i])) {
cipher = (word[i] + num - 97) % 26 + 97;
}
// all other types of characters
else {
cipher = word[i];
}
printf("%c", cipher);
}
printf("\n");
}
return 0;
}
// NOTE: I don't have GetString on my system
char *
FakeGetString(void)
{
static char buf[1000];
char *cp;
fgets(buf,sizeof(buf),stdin);
cp = strchr(buf,'\n');
if (cp != NULL)
*cp = 0;
return buf;
}
<强>更新
我写的上面的代码非常接近，但不是Vigenere，因为你的原始方程式已关闭。键值必须是偏移量/行号，因此需要从中减去'A'（即关键字只能是大写）。
所以，这是更正的版本[有一些额外的清理]：
#include <stdio.h>
#include <string.h>
#include <ctype.h>
// NOTE: I don't have GetString on my system
char *FakeGetString(void);
int
baseof(int chr)
{
int base;
// if original character is uppercase
if (isupper(chr)) {
base = 'A';
}
// if original character is lowercase
else if (islower(chr)) {
base = 'a';
}
// anything else
else
base = 0;
return base;
}
int
main(int argc, char *argv[])
{
int kval;
int base;
int i;
// key
// prompts if no key is entered
if (argc < 2) {
printf("Please enter your word key\n");
return 1;
}
char *key = argv[1];
int klen = strlen(key);
// key must be uppercase and we only want row numbers
for (i = 0; i < klen; ++i) {
kval = key[i];
base = baseof(kval);
if (base) {
key[i] = kval - base;
continue;
}
printf("Key value must be only A-Z\n");
return 1;
}
if (argc >= 2) {
printf("plaintext:");
#if 0
char *word = GetString();
#else
char *word = FakeGetString();
#endif
int wlen = strlen(word);
printf("ciphertext:");
// starts loop to repeat following for loop
// iterates through word entered by user as plaintext
// advance to next key char [with wrap to beginning if we're short]
for (i = 0; i < wlen; ++i) {
int wval = word[i];
int cipher;
base = baseof(wval);
// uppercase or lowercase
if (base) {
kval = key[i % klen];
cipher = ((wval - base) + kval) % 26 + base;
}
// all other types of characters
else {
cipher = wval;
}
printf("%c",cipher);
}
printf("\n");
}
return 0;
}
// NOTE: I don't have GetString on my system
char *
FakeGetString(void)
{
static char buf[1000];
char *cp;
fgets(buf,sizeof(buf),stdin);
cp = strchr(buf,'\n');
if (cp != NULL)
*cp = 0;
return buf;
}
更新＃2：
你的代码通过了所有check50检查，除了这一个:(加密“世界，打个招呼！”作为“xoqmd，rby gflkp！”使用“baz”作为关键字\期望输出，但不是“ciphertext：xoqmd，szz gflkp ！\ n“。它没有正确地加上'说'这个词，这很奇怪。
我使用Vigenere上维基百科页面中的测试数据/示例对其进行了测试，但它只有一个现成的测试示例[没有空格或标点符号]。
这是唯一包含空格的检查（在'说'之前）。必须直接复制空格。也许这就是原因。
空格是直接复制的，所以没关系。但是......
正确的方法是，当复制非alpha字符时，密钥索引必须不递增。
我的版本使用i索引短语，并使用i % klen索引密钥，因此密钥索引始终会有效地递增。这就是错误。
具有讽刺意味的是，我对此感到疑惑，但当时没有扩展的测试数据。
因此，解决方案是将索引变量[再次： - ）]分开。
这是更正后的版本。当我修复它时，我将i变量重命名为更具描述性的内容（例如widx），然后（重新）创建了密钥的索引变量（例如kidx）。
请注意，现在，kidx在实际加密字符时仅增加 。 “传递”案例不
#include <stdio.h>
#include <string.h>
#include <ctype.h>
// NOTE: I don't have GetString on my system
char *FakeGetString(void);
int
baseof(int chr)
{
int base;
// if original character is uppercase
if (isupper(chr)) {
base = 'A';
}
// if original character is lowercase
else if (islower(chr)) {
base = 'a';
}
// anything else
else
base = 0;
return base;
}
int
main(int argc, char *argv[])
{
int kval;
int base;
int widx;
int kidx;
// key
// prompts if no key is entered
if (argc < 2) {
printf("Please enter your word key\n");
return 1;
}
char *key = argv[1];
int klen = strlen(key);
// key must be uppercase and we only want row numbers
for (kidx = 0; kidx < klen; ++kidx) {
kval = key[kidx];
base = baseof(kval);
if (base) {
key[kidx] = kval - base;
continue;
}
printf("Key value must be only A-Z\n");
return 1;
}
if (argc < 2)
return 1;
printf("plaintext:");
#if 0
char *word = GetString();
#else
char *word = FakeGetString();
#endif
int wlen = strlen(word);
printf("ciphertext:");
kidx = 0;
// starts loop to repeat following for loop
// iterates through word entered by user as plaintext
// advance to next key char [with wrap to beginning if we're short]
for (widx = 0; widx < wlen; ++widx) {
int wval = word[widx];
int cipher;
base = baseof(wval);
// uppercase or lowercase
if (base) {
kval = key[kidx];
cipher = ((wval - base) + kval) % 26 + base;
kidx = (kidx + 1) % klen;
}
// all other types of characters
else {
cipher = wval;
}
printf("%c",cipher);
}
printf("\n");
return 0;
}
// NOTE: I don't have GetString on my system
char *
FakeGetString(void)
{
static char buf[1000];
char *cp;
fgets(buf,sizeof(buf),stdin);
cp = strchr(buf,'\n');
if (cp != NULL)
*cp = 0;
return buf;
}