initialized and declared
时间: 2023-05-02 07:00:26 浏览: 179
"initialized and declared"的意思是"已初始化和已声明"。当一个变量被声明时,它的数据类型被确定,但它的值没有被赋值。当一个变量被初始化时,它的值被第一次赋值。因此,一个已初始化的变量已经被赋予一个初始值,而一个已声明但未初始化的变量则没有。
相关问题
windows 如何解决warning: 'arr_json_key' initialized and declared 'extern'
在 Windows 平台上,可能会遇到以下警告:
```
warning: 'arr_json_key' initialized and declared 'extern'
```
这是因为在 C 语言中,初始化的变量不能同时声明为 `extern`,因为 `extern` 表示该变量是在其他文件中定义的。在 Windows 平台上,可以通过以下两种方法解决该警告:
1. 将变量声明为 `extern`,在另一个文件中定义该变量并初始化。
在变量声明的地方,使用 `extern` 关键字声明变量,如下所示:
```c
extern const char *arr_json_key[];
```
然后在另一个文件中定义该变量,并进行初始化,如下所示:
```c
const char *arr_json_key[] = {"key1", "key2", "key3"};
```
2. 在变量声明的地方,直接初始化变量。
在变量声明的地方,直接初始化变量,如下所示:
```c
const char *arr_json_key[] = {"key1", "key2", "key3"};
```
这样就不需要使用 `extern` 关键字了。
c语言 used without having been initialized
As an AI language model, I can explain what it means when a variable in C language is used without being initialized.
When a variable in C language is declared but not initialized, it contains garbage value, which means it can have any value. This value can be anything that was stored in the memory location previously. Therefore, if this variable is used without being initialized, it can lead to unexpected results.
For example, let's consider the following code:
```
int a;
printf("%d", a);
```
In this code, the variable "a" is declared but not initialized. When the printf statement tries to print the value of "a," it will print the garbage value stored in the memory location assigned to "a." This value can be anything, and the output will be unpredictable.
To avoid such issues, it is always recommended to initialize variables when they are declared. For example:
```
int a = 0;
printf("%d", a);
```
In this code, the variable "a" is initialized to 0 when it is declared, which ensures that it always contains a valid value.