I have TIA Portal v 14 SP1 Upd10

I cannot understand why this is happening. How to concatenate strings correctly in scripts

Ihave script:

Hi
What you have declared are not strings. They are pointers to strings.
char *str1 is a pointer that points to three characters:
"ab" + null
The null is to end the string.
The same happens for str2, str3 and str4.

The strings they are all pointing at will be bundled together in the local stack in the script procedure, one after the other.
They may be stored as:
"ab"+  null + "cd" + null + "ef" + null + "" + null + "" + null

They may be stored differently.

The problem is, you are not allowed to expand the strings, since you will overwrite memory that does not belong to the string.
Så when you write:
strcat(str4, str1);
you are putting "ab" into a string that is too short and is overwriting what is behind str4.

What you need to do is declare string variables instead of pointers:
char str1[40] = {"ab"};

This way you allocate 40 bytes to the string and can add more characters to the existing characters.
Just make sure you do not exceed the 40 bytes.


Best regards