Skip to main content

String Blocks

String Concat​

Introduction​

This block is used to concatenate multiple input strings in order into a new string. It can be used to combine several fragments or variables to be a merged string.

Attribute Description​

  • Input A ~ Input D: These are string segments to be joined in order (you can connect 1 to 4 strings as needed).
  • Output: The full new string after being concatenated in input order.

String Index Of​

Introduction​

The "String Index Of" logic block checks if one string appears in another string and gets the index position.

It's mainly used under the circumstances:

  • Analyzing string data reported by devices (such as status info, sensor callbacks, log content, etc.)
  • Checking if a specific field or keyword exists
  • Getting the start position of a keyword, so you can use this index for later logic

Attribute Description​

AttributeTypeRequired/OptionalDescription
OutputBooleanOutputWhether Input B string is found.
In AStringRequiredThe original string to search in.
In BStringRequiredThe substring to look for.
From IndexNumberOptionalThe index to start searching from. By default, it starts from 0.
Begin IndexNumberOutputThe index of the first occurrence of Input B in the original string. Returns -1 if not found.
After IndexNumberOutputIt can be used as the "From Index" when searching again, convenient for repeated searches.
tip

Indexing starts from 0.

Example​

Take "matching a single character" as an example, the steps are:

  1. Add a String Index Of block on the canvas.
  2. Set a string variable with the value 1234a567899999a and connect it to Input A of the block.
  3. Set another string variable with the value a and connect it to Input B of the block.
  4. Do not set From Index, so the search starts from 0 by default.
  5. After running, the block outputs:
    • Output (Boolean): true
    • Begin Index: 4
    • After Index: 5

From this example, you can see that string B is found at position 4 in string A for the first time. If you want to search again, you should set From Index to 5.

String Len​

Introduction​

Get the length of the specified string.

Attribute Description​

  • In: The string to query.
  • Output: The length of the string.

Substring​

Introduction​

Substring means extracting a section of characters from a string based on a begin index and an end index.

Attribute Description​

  • Default attributes displayed on the block:
    • In: The orignal string.
    • Output: The resulting substring after extraction.
  • Double-click the block to set the following attributes:
    • Begin Index: The starting position of the substring (inclusive, counting from 0).
    • End Index: The ending position of the substring (exclusive). If omitted, the substring goes to the end.

Example​

Here is an example of extracting a substring:

  1. Add a Substring block to the canvas.
  2. Set a string variable with the value Hello, Smart Home! and connect it to the In attribute of the Substring block.
  3. Set Begin Index to 0 and End Index to 5. This will extract characters from index 0 to index 4 (a total of 5 characters).
  4. After running, the block will output:
    • Output (Substring): Hello

If you want to extract another section, such as from index 7 to index 12, do the following:

  1. Set Begin Index to 7 and End Index to 12.
  2. After running, the block will output:
    • Output (Substring): Smart

From this example, you can see how to use the Substring logic block to extract a specific part of a string. If you want to extract until the end of the string, you can omit the End Index parameter.

String Trim​

Introduction​

String trim means removing whitespace from the start and end of a string. The content in the middle of the string is not affected.

Attribute Description​

  • In: The original string that needs to be trimmed.
  • Output: The trimmed string.

Example​

For "String Trim", the steps are:

  1. Add a String Trim block to the canvas.
  2. Set a string variable with the value temperature=24 , and connect it to the Input parameter of the block.
  3. After running, the block outputs:
    • Before trim: temperature=24
    • After trim (spaces at both ends removed): temperature=24