在处理不包含元音字母的 CS50 问题时，遇到了关于 strcat 的错误。

huangapple
go评论109阅读模式
英文:

doing the no-vowels cs50 problem and ran into an error with strcat

问题

在运行我的程序时，我遇到了错误：

  1. #include <cs50.h>
  2. #include <stdio.h>
  3. #include <string.h>
  5. int main(void)
  6. {
  7.     string word = get_string("给我一个单词：" );
  8.     int j = strlen(word);
  9.     int i;
  10.     char new[j + 1];
  12.     new[0] = '\0';
  13.     
  14.     for (i = 0; i < j; i++)
  15.     {
  16.         if (word[i] == 'e')
  17.         {
  18.             strcat(new, "3");
  19.         }
  20.         else if (word[i] == 'i')
  21.         {
  22.             strcat(new, "1");
  23.         }
  24.         else if (word[i] == 'a')
  25.         {
  26.             strcat(new, "6");
  27.         }
  28.         else if (word[i] == 'o')
  29.         {
  30.             strcat(new, "0");
  31.         }
  32.         else
  33.         {
  34.             char p = word[i];
  35.             strcat(new, p);
  36.         }
  37.     }
  38.     printf("%s\n", new);
  39. }

我得到了错误：

  1. no-vowels-test.c:39:25: error: incompatible integer to pointer conversion passing 'char' to parameter of type 'const char *'; take the address with & [-Werror,-Wint-conversion]
  2.             strcat(new, word[i]);
  3.                         ^~~~~~~
  4.                         &
  5. /usr/include/string.h:149:70: note: passing argument to parameter '__src' here
  6. extern char *strcat (char *__restrict __dest, const char *__restrict __src)

我的目标是使最后的 else 语句将数组中的当前字母 word[i] 追加到变量 new[] 中，以拼出一个新单词，在这个新单词中，每个元音字母都被数字替代，数字方面我没有问题。但是最后的 else 语句似乎有问题，我搞不清楚为什么。

英文:

When running my program:

  1. #include <cs50.h>
  2. #include <stdio.h>
  3. #include <string.h>
  5. int main(void)
  6. {
  7.     string word = get_string("Give me a word: " );
  8.     int j = strlen(word);
  9.     int i;
  10.     char new[j + 1];
  12.     new[0] = '
    #include <cs50.h>
  13. #include <stdio.h>
  14. #include <string.h>
  15. int main(void)
  16. {
  17. string word = get_string("Give me a word: " );
  18. int j = strlen(word);
  19. int i;
  20. char new[j + 1];
  21. new[0] = '\0';
  22. for (i = 0; i < j; i++)
  23. {
  24. if (word[i] == 'e')
  25. {
  26. strcat(new, "3");
  27. }
  28. else if (word[i] == 'i')
  29. {
  30. strcat(new, "1");
  31. }
  32. else if (word[i] == 'a')
  33. {
  34. strcat(new, "6");
  35. }
  36. else if (word[i] == 'o')
  37. {
  38. strcat(new, "0");
  39. }
  40. else
  41. {
  42. char p = word[i];
  43. strcat(new, p);
  44. }
  45. }
  46. printf("%s\n", new);
  47. }
  48. ';
  49.     
  50.     for (i = 0; i < j; i++)
  51.     {
  52.         if (word[i] == 'e')
  53.         {
  54.             strcat(new, "3");
  55.         }
  56.         else if (word[i] == 'i')
  57.         {
  58.             strcat(new, "1");
  59.         }
  60.         else if (word[i] == 'a')
  61.         {
  62.             strcat(new, "6");
  63.         }
  64.         else if (word[i] == 'o')
  65.         {
  66.             strcat(new, "0");
  67.         }
  68.         else
  69.         {
  70.             char p = word[i];
  71.             strcat(new, p);
  72.         }
  73.     }
  74.     printf("%s\n", new);
  75. }

I get the error:

  1. no-vowels-test.c:39:25: error: incompatible integer to pointer conversion passing 'char' to parameter of type 'const char *'; take the address with & [-Werror,-Wint-conversion]
  2.             strcat(new, word[i]);
  3.                         ^~~~~~~
  4.                         &
  5. /usr/include/string.h:149:70: note: passing argument to parameter '__src' here
  6. extern char *strcat (char *__restrict __dest, const char *__restrict __src)

My goal here is to make the last else statement append the current letter in the array of word[i] into the variable new[] to spell out a new word where every vowel is replaced by a number, the numbers I have no problem with. But the last else statement seems to have a problem and I cant figure out why.

答案1

得分: 2

要使用strcat，您需要提供一个指向以NUL结尾的字符串的指针。

  1. char s[2] = { word[i], 0 };
  2. strcat(new, s);

但您不需要使用strcat来添加单个字符，特别是因为您已经知道要写入字符的位置。您只需要使用new[i] = c;。只要完成后不要忘记用NUL终止您的字符串。

英文:

To use strcat, you would need to provide a pointer to a NUL-terminated string.

  1. char s[ 2 ] = { word[ i ], 0 };
  2. strcat( new, s );

But you don't need strcat to add a single character. Especially since you already know the position at which to write the character. All you need is new[ i ] = c;. Just don't forget to terminate your string with a NUL once you're done.

答案2

得分: 1

第二个参数传递给 strcat 必须是一个C字符串，即以空字符结尾的 char 数组，而不是一个单独的 char，比如 p。

你可以使用 strncat 来解决这个问题：将 strcat(new, p); 和前一行替换为：

  1. strncat(new, &word[i], 1);

这会将起始于 word[i] 的字符串的最多1个 char 连接起来。

另一种方法是直接设置 new 中的字节：

  1. #include <cs50.h>
  2. #include <stdio.h>
  3. #include <string.h>
  5. int main(void)
  6. {
  7.     string word = get_string("给我一个单词：");
  8.     int i;
  9.     int j = strlen(word);
  10.     char new[j + 1];
  12.     for (i = 0; i < j; i++)
  13.     {
  14.         if (word[i] == 'e')
  15.         {
  16.             new[i] = '3';
  17.         }
  18.         else if (word[i] == 'i')
  19.         {
  20.             new[i] = '1';
  21.         }
  22.         else if (word[i] == 'a')
  23.         {
  24.             new[i] = '6';
  25.         }
  26.         else if (word[i] == 'o')
  27.         {
  28.             new[i] = '0';
  29.         }
  30.         else
  31.         {
  32.             new[i] = word[i];
  33.         }
  34.     }
  35.     new[i] = '
    #include <cs50.h>
  36. #include <stdio.h>
  37. #include <string.h>
  39. int main(void)
  40. {
  41.     string word = get_string("给我一个单词：");
  42.     int i;
  43.     int j = strlen(word);
  44.     char new[j + 1];
  46.     for (i = 0; i < j; i++)
  47.     {
  48.         if (word[i] == 'e')
  49.         {
  50.             new[i] = '3';
  51.         }
  52.         else if (word[i] == 'i')
  53.         {
  54.             new[i] = '1';
  55.         }
  56.         else if (word[i] == 'a')
  57.         {
  58.             new[i] = '6';
  59.         }
  60.         else if (word[i] == 'o')
  61.         {
  62.             new[i] = '0';
  63.         }
  64.         else
  65.         {
  66.             new[i] = word[i];
  67.         }
  68.     }
  69.     new[i] = '\0';
  70.     printf("%s\n", new);
  71. }
  72. ';
  73.     printf("%s\n", new);
  74. }
英文:

The second argument to strcat must be a C string, ie: an array of char terminated with a null byte, not a single char such as p.

You can fix this problem with strncat: replace strcat(new, p); and the previous line with:

  1.     strncat(new, &amp;word[i], 1);

This concatenates at most 1 char from the string starting at word[i].

Another approach would set the bytes in new directly:

  1. #include &lt;cs50.h&gt;
  2. #include &lt;stdio.h&gt;
  3. #include &lt;string.h&gt;
  5. int main(void)
  6. {
  7.     string word = get_string(&quot;Give me a word: &quot; );
  8.     int i;
  9.     int j = strlen(word);
  10.     char new[j + 1];
  12.     for (i = 0; i &lt; j; i++)
  13.     {
  14.         if (word[i] == &#39;e&#39;)
  15.         {
  16.             new[i] = &#39;3&#39;;
  17.         }
  18.         else if (word[i] == &#39;i&#39;)
  19.         {
  20.             new[i] = &#39;1&#39;;
  21.         }
  22.         else if (word[i] == &#39;a&#39;)
  23.         {
  24.             new[i] = &#39;6&#39;;
  25.         }
  26.         else if (word[i] == &#39;o&#39;)
  27.         {
  28.             new[i] = &#39;0&#39;;
  29.         }
  30.         else
  31.         {
  32.             new[i] = word[i];
  33.         }
  34.     }
  35.     new[i] = &#39;
    #include &lt;cs50.h&gt;
  36. #include &lt;stdio.h&gt;
  37. #include &lt;string.h&gt;
  38. int main(void)
  39. {
  40. string word = get_string(&quot;Give me a word: &quot; );
  41. int i;
  42. int j = strlen(word);
  43. char new[j + 1];
  44. for (i = 0; i &lt; j; i++)
  45. {
  46. if (word[i] == &#39;e&#39;)
  47. {
  48. new[i] = &#39;3&#39;;
  49. }
  50. else if (word[i] == &#39;i&#39;)
  51. {
  52. new[i] = &#39;1&#39;;
  53. }
  54. else if (word[i] == &#39;a&#39;)
  55. {
  56. new[i] = &#39;6&#39;;
  57. }
  58. else if (word[i] == &#39;o&#39;)
  59. {
  60. new[i] = &#39;0&#39;;
  61. }
  62. else
  63. {
  64. new[i] = word[i];
  65. }
  66. }
  67. new[i] = &#39;\0&#39;;
  68. printf(&quot;%s\n&quot;, new);
  69. }
  70. &#39;;
  71.     printf(&quot;%s\n&quot;, new);
  72. }

huangapple
  • 本文由 发表于 2023年7月31日 22:17:27
  • 转载请务必保留本文链接：https://go.coder-hub.com/76804495.html
  • arrays
  • c
  • cs50
  • strcat
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定