Question

我有一个代码，使用g_file_set_contents在文件中写入一些长度为<length>的字符。当我打开文件时，我看到一些像@＆amp; @@似乎是ASCII的奇怪字符。我假设数据可能是用ASCII格式编写的，从二进制转换，所以我用一个函数从ASCII转换成二进制。执行后我仍然没有得到任何解决方案这是代码

#include <glib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char** argv) 
{

 FILE *file = g_fopen("Multicore","w");
 gchar *contents = 00001111;
 gchar **contents1 = NULL;
 GError *err = NULL;
 g_file_set_contents ("Multicore", &contents, 8, &err);
 g_assert ((contents == NULL && err != NULL) || (contents != NULL && err == NULL));
 if (err != NULL)
  {
    g_assert (contents == NULL);
    fprintf (stderr, "Unable to read file: %s\n", err->message);
    g_error_free (err);
  } 
 else
  {
    g_assert (contents != NULL);
  }
  int p = g_ascii_digit_value(contents);
  if (g_ascii_isdigit (contents))
    return contents - '0';
  return -1;
  g_printf(" The output is %c \n", contents);
  return 0;
}

我正确地输出

输出为00001111

Answer 1

你确实有很多错误。按照建议编译警告将有助于引导您注意需要修复的内容。解决最重要的问题（编译器无法找到g_fopen），例如：

debug.c:12:2: warning: implicit declaration of function ‘g_fopen’ [-Wimplicit-function-declaration]
  FILE *file = g_fopen("Multicore","w");
  ^
debug.c:12:15: warning: initialization makes pointer from integer without a cast [enabled by default]
  FILE *file = g_fopen("Multicore","w");
           ^

它告诉您缺少一个包含文件。快速检查会告诉您包括：`

#include <glib-object.h>
#include <glib/gstdio.h>

修复包含后，您会发现许多其他警告要解决：

debug.c: In function ‘main’:
debug.c:13:20: warning: initialization makes pointer from integer without a cast [enabled by default]
gchar *contents = 00001111;
                    ^
debug.c:16:2: warning: passing argument 2 of ‘g_file_set_contents’ from incompatible pointer type [enabled by default]
g_file_set_contents ("Multicore", &contents, 8, &err);
^
In file included from /usr/include/glib-2.0/glib.h:50:0,
                from debug.c:1:
/usr/include/glib-2.0/glib/gfileutils.h:91:10: note: expected ‘const gchar *’ but argument is of type ‘gchar **’
gboolean g_file_set_contents (const gchar *filename,
        ^
debug.c:28:3: warning: passing argument 1 of ‘g_ascii_digit_value’ makes integer from pointer without a cast [enabled by default]
int p = g_ascii_digit_value(contents);
^
In file included from /usr/include/glib-2.0/glib.h:81:0,
                from debug.c:1:
/usr/include/glib-2.0/glib/gstrfuncs.h:96:23: note: expected ‘gchar’ but argument is of type ‘gchar *’
gint                  g_ascii_digit_value  (gchar    c) G_GNUC_CONST;
                    ^
/usr/include/glib-2.0/glib/gstrfuncs.h:67:19: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
((g_ascii_table[(guchar) (c)] & G_ASCII_DIGIT) != 0)
                ^
debug.c:29:7: note: in expansion of macro ‘g_ascii_isdigit’
if (g_ascii_isdigit (contents))
    ^
debug.c:30:5: warning: return makes integer from pointer without a cast [enabled by default]
    return contents - '0';
    ^
debug.c:32:3: warning: format ‘%c’ expects argument of type ‘int’, but argument 2 has type ‘gchar *’ [-Wformat=]
g_printf(" The output is %c \n", contents);
^

依次对每个问题进行解决会使您的程序编译时只会警告未使用的变量，这不会影响其操作：

#include <glib.h>
#include <glib-object.h>
#include <glib/gstdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main (int argc, char **argv)
{

    FILE *file = g_fopen ("Multicore", "w");
    gchar *contents = "00001111";
    gchar **contents1 = NULL;
    GError *err = NULL;
    g_file_set_contents ("Multicore", contents, 8, &err);
    g_assert ((contents == NULL && err != NULL)
            || (contents != NULL && err == NULL));
    if (err != NULL) {
        g_assert (contents == NULL);
        fprintf (stderr, "Unable to read file: %s\n", err->message);
        g_error_free (err);
    } else {
        g_assert (contents != NULL);
    }
    int p = g_ascii_digit_value (*contents);
    if (g_ascii_isdigit (*contents))
        return *contents - '0';
    return -1;
    g_printf (" The output is %c \n", *contents);
    return 0;
}

使用

$ ./bin/debug

<强>输出

$ cat Multicore 00001111

根据需要，没有额外或奇怪的角色。

已启用警告的完整编译字符串

我正在使用的笔记本电脑上的完整编译字符串（openSuSE 13.1）利用pkg-config来保护必要的include / lib路径以及库本身。使用的编译字符串是：

gcc -Wall -Wextra -Ofast -o bin/debug debug.c \ `pkg-config --cflags --libs gtk+-2.0`

如果您没有pkgconfig，则扩展完整的编译字符串（插入行连续以便于阅读）将是：

gcc -Wall -Wextra -Ofast -o bin/debug debug.c -pthread -I/usr/include/gtk-2.0 \ -I/usr/lib64/gtk-2.0/include -I/usr/include/pango-1.0 -I/usr/include/atk-1.0 \ -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/libdrm \ -I/usr/include/libpng16 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng16 \ -I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0 \ -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/freetype2 \ -lgtk-x11-2.0 -lgdk-x11-2.0 -lpangocairo-1.0 -latk-1.0 -lcairo -lgdk_pixbuf-2.0 \ -lgio-2.0 -lpangoft2-1.0 -lpango-1.0 -lgobject-2.0 -lglib-2.0 -lfontconfig \ -lfreetype

使用glib在文件中写入的数据

1 个答案: