error storage size of ‘iw’ isn’t known

This error occurs when the compiler or interpreter is unable to determine the size of the variable 'iw'. It usually occurs when the variable is declared without specifying its size.

To fix this error, you can either specify the size of the variable 'iw' during declaration or use a data type whose size is known to the compiler. For example, if 'iw' is an integer, you can declare it as follows:

int iw = 0; // initialize to zero

If 'iw' is a float, you can declare it as follows:

float iw = 0.0; // initialize to zero

Alternatively, you can use a typedef to define a custom data type whose size is known to the compiler:

typedef unsigned short int myint;
myint iw = 0;

In this example, 'myint' is a custom data type that is equivalent to an unsigned short integer