Truncate

Consider a Python string that contains the letters "abcdef." But we only want the "abc" part. We need to truncate the string—slice syntax can be used.

Substring notes

With a first index of 0, we take a substring of the string from its start. We can omit the zero—Python assumes a zero in this case.

Truncation example

Here we have a string with three words in it. We first want to truncate the string to three characters. We use "0:3" to do this.

value = "one two three"

# Truncate the string to 3 characters.
first = value[0:3]
print(first + ".")

# Truncate the string to 7 characters.
second = value[0:7]
print(second + ".")
one.
one two.

Omit zero

As a Python developer, we grow tired of typing characters. The leading zero can be omitted for a truncation. Python assumes the "0:3" in this program.

letters = "abcdef"

# Omit the first 0 in the slice syntax.
# ... This truncates the string.
first_part = letters[:3]
print(first_part)
abc

Some notes

For negative values, our truncation method will truncate from the end of the string. This is the same as string slice syntax in Python.

No errors

In some languages like Java we will get exceptions with invalid indexes and lengths. This is not the case with Python—invalid indexes are reduces to be valid.

A review

String truncation requires no truncate() method call. A truncate() call exists but it is for file handling, not strings. We use string slices to truncate strings.