The role of auto in c language

The auto keyword declares local automatic storage variables in C language and has the following effects: Local scope: visible only within the scope of the function or block in which the variable is declared. Automatic storage: stored in the function stack, memory is allocated when the function is called and released when it returns. Default initialization: 0 for integer type, 0.0 for floating point type, and null character '\0' for character type. Can be used with any data type, including primitive types, arrays, and structures.

The role of the auto keyword in C language

The auto keyword declares local automatic storage in C language variable. It has the following effects:

1. Local scope
auto Variables declared are only visible within the scope of the function or block. Once outside that range, they are destroyed.

2. Automatic storage
auto variables are stored in the stack of the function. When the function is called, the system automatically allocates memory for these variables. When the function returns, the memory occupied by these variables will be released.

3. Default initialization
Variables declared by auto are initialized to 0 by default. For integer types it is 0; for floating point types it is 0.0; for character types it is the null character '\0'.

4. Variable type
The auto keyword can be used in conjunction with any data type, including basic types, arrays, and structures.

Example:

<code class="c">void myFunction() {
    auto int num;  // 声明一个局部整数变量 num

    num = 10;  // 赋值给 num

    printf("num is %d\n", num);  // 打印 num 的值
}</code>

In this example, the num variable is declared within the myFunction() function and is initialized to 0 by default. Then assign 10 to num and print its value. When the myFunction() function returns, the num variable will be destroyed.

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