如何使用'do while'循环重复'for'循环

Question

这是我的Vigenere密码代码。我正在尝试使用do while循环来重复遍历用户输入的键。密钥应用于用户输入的明文单词，一次一个字母。我需要能够遍历密钥直到明文单词结束，以防密钥短于单词。我试图使用do-while循环添加重复循环，第一个for循环是关键迭代。

'do while'循环的最后一行是抛出未声明标识符i的错误。这是我得到的唯一的错误。 'for'循环内部来自凯撒密码，并通过了所有检查。我认为我的while while循环是错误的。如果我添加char * word [i]或word [i]的定义，无论我在哪里放置它，都会产生遮蔽错误。我想使用这段代码，而不是彻底改变它，所以我明白如果可以这样做。但是，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) 
    } 
} 

Answer 1

我觉得你有太多的循环[levels]。

如果密钥长度在单词结束之前用完，则重新开始加密单词开头的中的单词（即错误）。

主要的重点是循环所有字词。 A 单个循环递增i工作，提供它也递增l [模数键长度]。

这里有一个清理版本[请原谅无偿风格清理]：

#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; 
} 

---

UPDATE：

上面的代码我写的是很接近，但没有的V @ genere因为你的原始方程已关闭。键值必须是偏移/行号，因此需要从中减去'A'（即关键字只能是大写）。

所以，这里是修正版本[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：

您的代码通过了所有check50检查，除了这一个： :(使用“baz”作为关键字\期望的输出，而不是“密文：xoqmd，szz gflkp！\”来加密“世界，打个招呼！”为“xoqmd，rby gflkp！”，它不会加密单词'正确地说'，这就是伟RD。

我测试使用来自上的V @ genere维基百科页测试数据/例子，但它只有一个准备试验例[而不空格或标点。

这是包含一个空格（在“say”之前）的唯一检查。空间必须直接复制。也许这就是原因。

的空间为直接复制，所以这是好的。但是...

正确的方法是，当复制非字母字符时，密钥索引必须增加而不是。

我的版本中使用i索引的语句和i % klen索引的关键，所以关键指标将总是递增[有效。这是错误。

讽刺的是，我已经不知道这一点，但没有在当时展开的测试数据。

因此，解决方案是[再:-)]分离索引的变量。

这里的修正版本。当我将其固定我改名i变量为更具说明性的（例如widx）和（重新）创建的索引变量的密钥（例如kidx）。

请注意，现在kidx是只有在实际加密字符时递增。在“通过”的情况下不不

#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; 
}