Question

对不起，我的英语不好。我使用Raspberry pi 3的示例代码。我尝试在代码块上运行示例代码，我需要学习。我基于示例代码的Makefile配置了调试设置。我配置链接器设置。当我在代码块上构建代码时，它没有显示错误。但是当我运行代码时。我在控制台上出错。错误提示：

字体示例：/ home / pi / Desktop /字体示例/main.c：101：main：Assertion's == 0'失败。

我说了句。编写此代码：

// Test app for VG font library.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>

#include "/opt/vc/src/hello_pi/libs/vgfont/bcm_host.h"
#include "/opt/vc/src/hello_pi/libs/vgfont/vgfont.h"

static const char *strnchr(const char *str, size_t len, char c)
{
   const char *e = str + len;
   do {
      if (*str == c) {
         return str;
      }
   } while (++str < e);
   return NULL;
}

int32_t render_subtitle(GRAPHICS_RESOURCE_HANDLE img, const char *text, const int skip, const uint32_t text_size, const uint32_t y_offset)
{
   uint32_t text_length = strlen(text)-skip;
   uint32_t width=0, height=0;
   const char *split = text;
   int32_t s=0;
   int len = 0; // length of pre-subtitle
   uint32_t img_w, img_h;

   graphics_get_resource_size(img, &img_w, &img_h);

   if (text_length==0)
      return 0;
   while (split[0]) {
      s = graphics_resource_text_dimensions_ext(img, split, text_length-(split-text), &width, &height, text_size);
      if (s != 0) return s;
      if (width > img_w) {
         const char *space = strnchr(split, text_length-(split-text), ' ');
         if (!space) {
            len = split+1-text;
            split = split+1;
         } else {
            len = space-text;
            split = space+1;
         }
      } else {
         break;
      }
   }
   // split now points to last line of text. split-text = length of initial text. text_length-(split-text) is length of last line
   if (width) {
      s = graphics_resource_render_text_ext(img, (img_w - width)>>1, y_offset-height,
                                     GRAPHICS_RESOURCE_WIDTH,
                                     GRAPHICS_RESOURCE_HEIGHT,
                                     GRAPHICS_RGBA32(0xff,0xff,0xff,0xff), /* fg */
                                     GRAPHICS_RGBA32(0,0,0,0x80), /* bg */
                                     split, text_length-(split-text), text_size);
      if (s!=0) return s;
   }
   return render_subtitle(img, text, skip+text_length-len, text_size, y_offset - height);
}

int main(void)
{
   GRAPHICS_RESOURCE_HANDLE img;
   uint32_t width, height;
   int LAYER=1;
   bcm_host_init();
   int s;

   s = gx_graphics_init(".");
   assert(s == 0);                  //101. line

   s = graphics_get_display_size(0, &width, &height);
   assert(s == 0);

   s = gx_create_window(0, width, height, GRAPHICS_RESOURCE_RGBA32, &img);
   assert(s == 0);

   // transparent before display to avoid screen flash
   graphics_resource_fill(img, 0, 0, width, height, GRAPHICS_RGBA32(0,0,0,0x00));

   graphics_display_resource(img, 0, LAYER, 0, 0, GRAPHICS_RESOURCE_WIDTH, GRAPHICS_RESOURCE_HEIGHT, VC_DISPMAN_ROT0, 1);

   uint32_t text_size = 10;
   while (1) {
      const char *text = "The quick brown fox jumps over the lazy dog";
      uint32_t y_offset = height-60+text_size/2;
      graphics_resource_fill(img, 0, 0, width, height, GRAPHICS_RGBA32(0,0,0,0x00));
      // blue, at the top (y=40)
      graphics_resource_fill(img, 0, 40, width, 1, GRAPHICS_RGBA32(0,0,0xff,0xff));

      // green, at the bottom (y=height-40)
      graphics_resource_fill(img, 0, height-40, width, 1, GRAPHICS_RGBA32(0,0xff,0,0xff));

      // draw the subtitle text
      render_subtitle(img, text, 0, text_size,  y_offset);
      graphics_update_displayed_resource(img, 0, 0, 0, 0);
      text_size += 1;
      if (text_size > 50)
         text_size = 10;
   }

   graphics_display_resource(img, 0, LAYER, 0, 0, GRAPHICS_RESOURCE_WIDTH, GRAPHICS_RESOURCE_HEIGHT, VC_DISPMAN_ROT0, 0);
   graphics_delete_resource(img);

   return 0;
}

1-怎么了？
2-为什么在控制台上出现此错误，为什么在编译器上看不到？

注意：：我可以在终端上运行此代码（使用make后先进入文件并在控制台上使用./hello_font.bin）可以正常工作。

谢谢您的时间。最好的问候。

Answer 1

1-怎么了？
2-为什么在控制台上出现此错误，为什么在编译器上看不到？

您使用的assert是运行时断言。
如果需要编译时声明，则必须使用static_assert.
使用static_assert可让您打印自己的消息，该消息将显示为编译器错误。

简单的例子：

int main()
{
    static_assert(0 == 1, "Zero is not equal to one");
}

编译器输出：

main.cpp: In function 'int main()':
main.cpp:3:21: error: static assertion failed: Zero is not equal to one
     static_assert(0 == 1, "Zero is not equal to one");

Answer 2

与@Scheff的评论一样。您应该添加宏。我添加了NDEBUG宏（在我的项目构建设置上，并将宏添加到了选项下其他编译器的选项卡上）。所以我的问题解决了。

带有Linux的代码块上的断言“值”失败

2 个答案: