tf.compat.v1.strings.length

Computes the length of each string given in the input tensor.

tf.compat.v1.strings.length(
    input, name=None, unit='BYTE'
)

strings = tf.constant(['Hello','TensorFlow', '????'])
tf.strings.length(strings).numpy() # default counts bytes
array([ 5, 10, 4], dtype=int32)
tf.strings.length(strings, unit="UTF8_CHAR").numpy()
array([ 5, 10, 1], dtype=int32)

Args
input	A Tensor of type string. The strings for which to compute the length for each element.
name	A name for the operation (optional).
unit	An optional string from: "BYTE", "UTF8_CHAR". Defaults to "BYTE". The unit that is counted to compute string length. One of: "BYTE" (for the number of bytes in each string) or "UTF8_CHAR" (for the number of UTF-8 encoded Unicode code points in each string). Results are undefined if unit=UTF8_CHAR and the input strings do not contain structurally valid UTF-8.

Returns
A Tensor of type int32, containing the length of the input string in the same element of the input tensor.