How to use auto in c language

The auto keyword is used to declare local variables in C language. It has the following functions: declare local variables, which default to int type and are automatically initialized to 0 after declaration.

Usage of auto keyword in C language

auto keyword is used to declare local in C language A storage class specifier for a variable. Local variables are declared within a function or block and are valid only within that function or block. The auto keyword can be used to declare various data types such as integers, floating point numbers, characters, and structures.

The role of auto

The auto keyword has the following functions:

• Tell the compiler that the variable is a local variable.
• The default is int data type.
• Variables are automatically initialized to 0 after declaration.

Usage of auto

The usage of auto keyword is as follows:

<code class="c">auto var_name;</code>

where var_name is the variable name.

Comparison of auto and register keywords

auto and register are both storage class specifiers for local variables, but there are subtle differences between them:

• The auto keyword will not be stored in a register, but the register keyword will.
• Register keyword variables cannot be addressed by the address operator (&), but auto keyword variables can.

Example

The following example shows the use of the auto keyword:

<code class="c">#include <stdio.h>

int main() {
  auto int i;
  auto float f;

  i = 10;
  f = 20.5;

  printf("i = %d\n", i);
  printf("f = %f\n", f);

  return 0;
}</code>

Output:

<code>i = 10
f = 20.500000</code>

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