2023年3月23日 11:48:19go评论72阅读模式

英文:

Char Arrays code in C Programming Book example not working

问题

我正在研究Brian Kernighan和Dennis Ritchie的《C编程语言第二版》，书中提供的第1.9章中关于字符数组的代码对我不起作用。我确定这不是书的问题，所以肯定是我遗漏了某些东西。但我无法弄清楚是什么。我的代码检查工具没有给我任何错误，但当我尝试编译它时，出现了一堆错误。

错误：

scratch.c:4:5: error: conflicting types for 'getline'
int getline(char line[], int maxline);
    ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdio.h:365:9: note: previous declaration is here
ssize_t getline(char ** __restrict __linep, size_t * __restrict __linecapp, FILE * __restrict __stream) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
        ^
scratch.c:15:40: error: too few arguments to function call, expected 3, have 2
    while ((len = getline(line, MAXLINE)) > 0) {
                  ~~~~~~~              ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdio.h:365:9: note: 'getline' declared here
ssize_t getline(char ** __restrict __linep, size_t * __restrict __linecapp, FILE * __restrict __stream) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
        ^
scratch.c:26:5: error: conflicting types for 'getline'
int getline(char s[], int lim) {
    ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdio.h:365:9: note: previous declaration is here
ssize_t getline(char ** __restrict __linep, size_t * __restrict __linecapp, FILE * __restrict __stream) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);

我的代码

#include <stdio.h>
#define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main() {
    int len; 
    int max;
    char line[MAXLINE];
    char longest[MAXLINE];

    max = 0;

    while ((len = getline(line, MAXLINE)) > 0) {
        if (len > max) {
            max = len;
            copy(longest, line);
        }
    }
    if (max > 0)
        printf("%s", longest);
    return 0;
}

int getline(char s[], int lim) {
    int c, i;

    for (i=0; i<lim-1 && (c=getchar()) != EOF && c != '\n'; ++i) {
        s[i] = c;
    }
    if (c == '\n') {
        s[i] = c;
        ++i;
    }

    s[i] = '#include <stdio.h>
#define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main() {
    int len; 
    int max;
    char line[MAXLINE];
    char longest[MAXLINE];

    max = 0;

    while ((len = getline(line, MAXLINE)) > 0) {
        if (len > max) {
            max = len;
            copy(longest, line);
        }
    }
    if (max > 0)
        printf("%s", longest);
    return 0;
}

int getline(char s[], int lim) {
    int c, i;

    for (i=0; i<lim-1 && (c=getchar()) != EOF && c != '\n'; ++i) {
        s[i] = c;
    }
    if (c == '\n') {
        s[i] = c;
        ++i;
    }

    s[i] = '\0';
    return i;
}

void copy(char to[], char from[]) {
    int i;
    i = 0;
    while ((to[i] = from[i]) != '\0')
    ++i;
}
';
    return i;
}

void copy(char to[], char from[]) {
    int i;
    i = 0;
    while ((to[i] = from[i]) != '#include <stdio.h>
#define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main() {
    int len; 
    int max;
    char line[MAXLINE];
    char longest[MAXLINE];

    max = 0;

    while ((len = getline(line, MAXLINE)) > 0) {
        if (len > max) {
            max = len;
            copy(longest, line);
        }
    }
    if (max > 0)
        printf("%s", longest);
    return 0;
}

int getline(char s[], int lim) {
    int c, i;

    for (i=0; i<lim-1 && (c=getchar()) != EOF && c != '\n'; ++i) {
        s[i] = c;
    }
    if (c == '\n') {
        s[i] = c;
        ++i;
    }

    s[i] = '\0';
    return i;
}

void copy(char to[], char from[]) {
    int i;
    i = 0;
    while ((to[i] = from[i]) != '\0')
    ++i;
}
')
    ++i;
}

英文:

I'm working on Brian Kernighan and Dennis Ritchie's C Programming Language 2nd Edition, and the code provided on 1.9, on character arrays, isn't working for me. I'm sure it's not a problem with the book, so I must be missing something. But I can't figure out what. My linter is not giving me any errors, but when I try to compile it, I get a bunch of errors.

Errors:

scratch.c:4:5: error: conflicting types for &#39;getline&#39;
int getline(char line[], int maxline);
    ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdio.h:365:9: note: previous declaration is here
ssize_t getline(char ** __restrict __linep, size_t * __restrict __linecapp, FILE * __restrict __stream) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
        ^
scratch.c:15:40: error: too few arguments to function call, expected 3, have 2
    while ((len = getline(line, MAXLINE)) &gt; 0) {
                  ~~~~~~~              ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdio.h:365:9: note: &#39;getline&#39; declared here
ssize_t getline(char ** __restrict __linep, size_t * __restrict __linecapp, FILE * __restrict __stream) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
        ^
scratch.c:26:5: error: conflicting types for &#39;getline&#39;
int getline(char s[], int lim) {
    ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdio.h:365:9: note: previous declaration is here
ssize_t getline(char ** __restrict __linep, size_t * __restrict __linecapp, FILE * __restrict __stream) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);

my code

#include &lt;stdio.h&gt;
#define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main() {
    int len; 
    int max;
    char line[MAXLINE];
    char longest[MAXLINE];

    max = 0;

    while ((len = getline(line, MAXLINE)) &gt; 0) {
        if (len &gt; max) {
            max = len;
            copy(longest, line);
        }
    }
    if (max &gt; 0)
        printf(&quot;%s&quot;, longest);
    return 0;
}

int getline(char s[], int lim) {
    int c, i;

    for (i=0; i&lt;lim-1 &amp;&amp; (c=getchar()) != EOF &amp;&amp; c != &#39;\n&#39;; ++i) {
        s[i] = c;
    }
    if (c == &#39;\n&#39;) {
        s[i] = c;
        ++i;
    }

    s[i] = &#39;#include &lt;stdio.h&gt;
#define MAXLINE 1000
int getline(char line[], int maxline);
void copy(char to[], char from[]);
int main() {
int len; 
int max;
char line[MAXLINE];
char longest[MAXLINE];
max = 0;
while ((len = getline(line, MAXLINE)) &gt; 0) {
if (len &gt; max) {
max = len;
copy(longest, line);
}
}
if (max &gt; 0)
printf(&quot;%s&quot;, longest);
return 0;
}
int getline(char s[], int lim) {
int c, i;
for (i=0; i&lt;lim-1 &amp;&amp; (c=getchar()) != EOF &amp;&amp; c != &#39;\n&#39;; ++i) {
s[i] = c;
}
if (c == &#39;\n&#39;) {
s[i] = c;
++i;
}
s[i] = &#39;\0&#39;;
return i;
}
void copy(char to[], char from[]) {
int i;
i = 0;
while ((to[i] = from[i]) != &#39;\0&#39;)
++i;
}
&#39;;
    return i;
}

void copy(char to[], char from[]) {
    int i;
    i = 0;
    while ((to[i] = from[i]) != &#39;#include &lt;stdio.h&gt;
#define MAXLINE 1000
int getline(char line[], int maxline);
void copy(char to[], char from[]);
int main() {
int len; 
int max;
char line[MAXLINE];
char longest[MAXLINE];
max = 0;
while ((len = getline(line, MAXLINE)) &gt; 0) {
if (len &gt; max) {
max = len;
copy(longest, line);
}
}
if (max &gt; 0)
printf(&quot;%s&quot;, longest);
return 0;
}
int getline(char s[], int lim) {
int c, i;
for (i=0; i&lt;lim-1 &amp;&amp; (c=getchar()) != EOF &amp;&amp; c != &#39;\n&#39;; ++i) {
s[i] = c;
}
if (c == &#39;\n&#39;) {
s[i] = c;
++i;
}
s[i] = &#39;\0&#39;;
return i;
}
void copy(char to[], char from[]) {
int i;
i = 0;
while ((to[i] = from[i]) != &#39;\0&#39;)
++i;
}
&#39;)
    ++i;
}

答案1

得分: 1

The problem is that your program uses the identifier getline.

问题在于你的程序使用了标识符 getline。

The ISO C standard (any edition) does not define getline, but POSIX does -- and POSIX (a secondary standard) specifies that the getline function is declared in <stdio.h>, one of the standard headers defined by the ISO C standard.

ISO C标准（任何版本）没有定义 getline，但POSIX定义了，而POSIX（次要标准）规定 getline 函数声明在 <stdio.h> 中，这是ISO C标准定义的标准头文件之一。

This is IMHO unfortunate, but it's the way it is.

在我看来，这很不幸，但事实就是如此。

Many C compilers are not conforming by default. gcc and clang (you're likely using the latter) support a number of extensions unless you tell them not to, including functions defined by POSIX.

许多C编译器默认情况下不符合标准。gcc和clang（你可能正在使用后者）支持许多扩展，除非你告诉它们不要支持，包括由POSIX定义的函数。

You can compile with -std=c90 to ask the compiler to conform to the 1990 ISO C standard (the version of the standard used by the book you're using); -std=c89 and -ansi are equivalent. Or you can ask it to conform to a later standard: -std=c99, or -std=c11, or -std-c17. (These options still don't fully conform to the named C standard; you need to add -pedantic for that, to get all required diagnostics.)

你可以使用 -std=c90 编译，要求编译器符合1990年的ISO C标准（你使用的书籍使用的标准版本）；-std=c89 和 -ansi 是等效的。或者你可以要求它符合更高版本的标准：-std=c99、-std=c11 或 -std-c17。（这些选项仍然不完全符合所命名的C标准；为此，你需要添加 -pedantic 以获取所有所需的诊断信息。）

The details may differ if you're using a different compiler. C compilers on Unix-like systems tend to try to mimic gcc's behavior, but for example Microsoft's compiler does not. Consult your compiler's documentation if necessary.

如果你使用不同的编译器，细节可能会有所不同。类Unix系统上的C编译器往往会尝试模仿gcc的行为，但例如Microsoft的编译器则不会。如有必要，请查阅你的编译器文档。

Another option is to change your function's name from getline to something else, like get_line, which is not reserved.

另一种选择是将你的函数名称从 getline 更改为其他名称，比如 get_line，这不是保留字。

英文:

The problem is that your program uses the identifier getline.

This is IMHO unfortunate, but it's the way it is.

Many C compilers are not conforming by default. gcc and clang (you're likely using the latter) support a number of extensions unless you tell them not to, including functions defined by POSIX.

Another option is to change your function's name from getline to something else, like get_line, which is not reserved.

答案2

得分: 0

我一定是漏掉了什么。但我想不出是什么。

正如其他人已经评论的那样，问题在于你所使用的书非常老旧。

在它被发布后，标准的 getline 程序已经被引入，而你（或书中的）的 getline 与标准的冲突。

将 getline 重命名为例如 my_getline 是最简单的解决方法。

使用更新的书也是另一个可能性。

英文:

> I must be missing something. But I can't figure out what.

As others have commented, the problem is that the book you are following is really old.

After it has been published, a standard getline routine has been introduced, and your (or the book's) getline conflicts with the standard one.

Renaming getline to e.g. my_getline in your source is the easiest solution.

Using a newer book is another possibility.

通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。

Char Arrays code in C Programming Book example not working.

问题

答案1

答案2

当静态库需要位置无关代码

How to access the address of a function I bring from a shared object in a debugger using ELF file, RELA and then finding it in GOT?

ArrayList vs String[], How and when to use?

How can I create a New numpy array of matrix dimensions 1×3,1×3 and 1×1 using an already existing 2D array containing 7 elements?

What's the correct way to type hint an empty list as a literal in python?

如何在Highcharts Gantt中更改本地化的星期名称

如何在同一个流中使用多个过滤器和映射函数？

如何使用Map/Set来将代码优化到O(n)？

.NET MAUI Android在GitHub Actions上构建失败，错误代码为1。

如何在Playwright视觉比较中屏蔽多个定位器？

在C++中，可以使用可变模板参数来检索类型的内部类型。

selenium.common.exceptions.StaleElementReferenceException: Message: stale element reference: stale element not found

Creating and opening a URL to log in to Website via Basic Auth with Robot Framework/Selenium (Python)

AG Grid 在上下文菜单中以大文本形式打开

发表评论