Python *args and **kwargs
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What is *args ??
*args allows us to pass variable number of arguments to the function. Let’s take an example to make this clear.
Suppose you created a function to add two number like this.
| 12 | defsum(a,b): print("sum is",a+b) |
As you can see this program only accepts two numbers, what if you want to pass more than two arguments, this is where *args comes into play.
| 12345 | defsum(*args): s=0 foriinargs: s+=i print("sum is",s) |
Now you can pass any number of arguments to the function like this,
| 12345678 | >>>sum(1,2,3)6>>> |
Note: name of *args is just a convention you can use anything that is a valid identifier. For e.g *myargs is perfectly valid.
What is **kwargs ?
**kwargs allows us to pass variable number of keyword argument like this func_name(name='tim',team='school')
| 12345 | defmy_func(**kwargs): fori,jinkwargs.items(): print(i,j)my_func(name='tim',sport='football',roll=19) |
Expected Output:
| 123 | sport footballroll19name tim |
Using *args and **kwargs in function call
You can use *args to pass elements in an iterable variable to a function. Following example will clear everything.
| 12345 | defmy_three(a,b,c): print(a,b,c)a=[1,2,3]my_three(*a)# here list is broken into three elements |
Note: This works only when number of argument is same as number of elements in the iterable variable.
Similarly you can use **kwargs to call a function like this
| 12345 | defmy_three(a,b,c): print(a,b,c)a={'a':"one",'b':"two",'c':"three"}my_three(**a) |
Note: For this to work 2 things are necessary:
- Names of arguments in function must match with the name of keys in dictionary.
- Number of arguments should be same as number of keys in the dictionary.
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