CODESYS permits the index access ‎[]‎ to variables of type ‎POINTER TO‎, as well as to the data types ‎STRING‎ or ‎WSTRING‎.

The data, which the pointer points to, can also be accessed by appending the bracket operator ‎[]‎ to the pointer identifier(for example, ‎piData[i]‎). The base data type of the pointer determines the data type and the size of the indexed component. In this case, the index access to the pointer is done arithmetically by adding the index dependent offset ‎i * SIZEOF(<base type>)‎ to the address of the pointer. The pointer is dereferenced implicitly at the same time.

Calculation:

piData[i] := (piData + i * SIZEOF(INT))^;

That is not not:

piData[i] != (piData + i)^;

Index access

When you use the index access with a variable of the type ‎STRING‎, you get the character at the offset of the index expression. The result is of type ‎BYTE‎. For example, ‎sData[i]‎ returns the i-th character of the string ‎sData‎ as ‎SINT‎ (ASCII).

Index access

When you use the index access with a variable of the type ‎WSTRING‎, you get the character at the offset of the index expression. The result is of type ‎WORD‎. For example, ‎wsData[i]‎ returns the i-th character of the string as ‎INT‎ (Unicode).