How to Fix SyntaxError: positional argument follows keyword argument in Python

A SyntaxError indicates that the Python interpreter has found code that does not conform to the correct syntax of the language. One common form is:

SyntaxError: positional argument follows keyword argument

This error typically occurs during a function call when a positional argument is placed after a keyword argument, which is not allowed in Python. Example:

# function definition
def fun(a, b, c=5):
    print(a, b, c)

# invalid call
fun(a=1, 2, c=3)

Output

  File "main.py", line 6
    fun(a=1, 2, c=3)
             ^
SyntaxError: positional argument follows keyword argument

Explanation: Here, a=1 is a keyword argument, but 2 is a positional argument that comes after it. Python does not allow positional arguments after keyword arguments in a function call.

How to fix It

Move all positional arguments before keyword arguments in the function call:

fun(1, 2, c=3)

Keyword and Positional Arguments in Python

In Python, function arguments can be passed in two ways:

• Positional Arguments: Identified by their position in the function definition.
• Keyword Arguments: Identified by the name of the parameter (i.e., key=value pairs).

Example 1 : Valid Function calls

def fun(a, b, c=10):
    print(f"a={a}, b={b}, c={c}")

# all positional
fun(2, 3, 8)

# Positional with default
fun(2, 3)

# ALl keyword arguments
fun(a=2, c=3, b=10)

a=2, b=3, c=8
a=2, b=3, c=10
a=2, b=10, c=3

Explanation:

• fun takes three parameters a, b and an optional c with a default value of 10. It prints their values using f-string
• fun(2, 3, 8) Values are assigned by order: a=2, b=3, c=8.
• fun(2, 3) Since c isn’t provided, it defaults to 10: a=2, b=3, c=10.
• fun(a=2, c=3, b=10) Order doesn’t matter as each value is tied to a parameter: a=2, b=10, c=3.

Example 2: Invalid function calls

# Function definition
def fun(a, b, c=10):
    print('a =', a)
    print('b =', b)
    print('c =', c)

# Invalid function call
print("Call 4")
fun(a=2, c=3, 9)

Output

Hangup (SIGHUP)
  File "Solution.py", line 9
    fun(a=2, c=3, 9)
SyntaxError: non-keyword arg after keyword arg

Explanation: fun(a=2, c=3, 9), a=2 and c=3 are keyword arguments, but 9 is a positional argument placed after them. Python disallows this because positional arguments must come before any keyword arguments for reliable parameter matching.

To fix it, place all positional arguments first:

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