undefined definition/reference

"undefined" 通常是指某个值或变量没有被赋值或定义。如果一个变量被声明但没有被赋值，那么它的值将是 "undefined"。这也可以用来指示一个对象中缺少所需的属性或方法。在计算机编程中，"undefined" 是一个特殊值，它表示缺少值或不存在。在使用 "undefined" 的情况下，通常需要检查变量或值是否已经定义或赋值，以避免潜在的错误。

相关问题

undefined definition reference

undefined definition reference是一个编程术语，指的是某个变量、函数或对象的定义未被找到或未被识别。通常会导致编译错误或链接错误。在引用中，报错"undefined reference to vtable for classname"是因为在使用Qt自带的信号与槽机制时，需要将自定义的类继承自QObject并添加Q_OBJECT宏，但可能在编译过程中没有正确链接到相关的库文件。可以检查是否在.pro文件中正确添加了相关的模块。

在引用中，报错"source browser: 'xxxx' undefined definition/reference"是因为在编写DMA的初始化函数时，忘记添加了一个名为stmf10x_dma.c的文件，导致无法找到对应的定义。通过在FWLib文件夹下添加stm32f10x_dma.c文件后，问题得到解决。

对于其他类似的错误，如引用中的"TypeError: $.browser is undefined"，通常是因为使用了过时的jQuery插件或存在兼容性问题。解决此类问题可以尝试更新或更换插件版本，或者参考相关文档和讨论来找到合适的解决方法。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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undefined reference to

This error message typically occurs during the linking phase of compiling a program. It means that the compiler was unable to find a definition for a function or variable that was declared in the code.

Possible causes include:

- A typo in the function or variable name
- Missing include files or libraries
- The function or variable was not defined in the source code
- The function or variable was defined in a different file, but that file was not included in the compilation process
- The function or variable was defined in a library that was not linked to the program

To fix this error, you need to ensure that the function or variable is defined and that it is accessible to the compiler. This may involve checking your code for typos or missing include files, or adding the necessary library or source files to the compilation process.