How can I write results into the passed parameters (arguments)?
### permutation function
def xchg(a, b):
""" xchg function that does a permution for two integers
"""
a=a+b
b=a-b
a=a-b
a=int(input("Enter a number: "))
b=int(input("Enter another number: "))
xchg(a,b)
print("a= ", a)
print("b= ", b)
If you're learning Python, you should learn how to write Python, not learn how to write C or Java in Python.
In Python, there is no point in doing this. Much better:
b, a = a, b
You should know that what you're trying to do is not possible.
In Python, there are values and there are names (variables).
An assignment makes a name refer to a value. It follows, that the same value can have multiple names.
Function parameters are names, that are local to that function. Assigning to them cannot make a different name magically refer to a different value. All it does is "bind" the local name to a different value.
Now, there are mutable values, and there are immutable values. Remember, different names can refer to the same value. If you change the value, rather than bind a name to a different value, all other names that are bound to that value will see the change, too.
### permutation function def xchg(a, b): """ xchg function that does a permution for two integers """ a=a+b b=a-b a=a-b return a, b a=int(input("Enter a number: ")) b=int(input("Enter another number: ")) a,b=xchg(a,b) print("a= ", a) print("b= ", b)
def xchg(a, b): return b, a In Pyhton there is not need for the C/assembler style im-place swap pattern!
Try:
def xchg(a, b):
return b, a
and then later:
a, b = xchg(a, b)
aandbvariables change scope due to the function. Thereforeaandbswitch only within the scope ofxchg. You'd have to return a value and assign that value to a variable if you wanted this to work. For future information, this has to do with mutability of datatypes in python.