# A Complete Tutorial for Python’s += Operator

In this session, we’ll look at Python’s += operator. Let us see how it works with a few simple examples.

The addition assignment operator is denoted by the operator ‘+=’. It is like a short form to it. It adds two values and stores the result in a variable (left operand).

#### Addition of Two numbers Using += Operator:

Example1:

gvn_num = 100
print("The given number = ", gvn_num)
gvn_num += 50
print("The given number after addition with 50 = ", gvn_num)


Output:

The given number =  100
The given number after addition with 50 =  150

Example2:

a = 10
b = 20
c = 30
rslt_sum = 0
# Adding a,b,c and storing it in a variable rslt_sum
# The below indicates rslt_sum = rslt_sum+(a+b+c)
rslt_sum += a+b+c
print("The sum of a,b,c = ", rslt_sum)


Output:

The sum of a,b,c =  60

#### For Strings

The ‘+=’ operator concatenates the given strings. It is used for the concatenation of two or more strings.

Example1:

gvn_fststr = "hello"
gvn_scndstr = "btechgeeks"
print("The given first string = ", gvn_fststr)
print("The given second string = ", gvn_scndstr)
print()
# It concatenates the given first string with the second string and assigns the
# result to the first string
gvn_fststr += gvn_scndstr

print("The given first string after concatenation = ", gvn_fststr)


Output:

The given first string =  hello
The given second string =  btechgeeks

The given first string after concatenation =  hellobtechgeeks

Example2:

gvn_fststr = "hello"
gvn_scndstr = " this is "
gvn_thrdstr = "btechgeeks"
concat_str = ""
# concatenating the given three strings using  '+=' Operator
concat_str += (gvn_fststr+gvn_scndstr+gvn_thrdstr)
print("The concatenation of given three strings = ", concat_str)


Output:

The concatenation of given three strings =  hello this is btechgeeks

#### The “+=” operator’s Associativity in Python

The ‘+=’ operator’s associativity property is from right to left.

Example1:

a = 3
b = 6
a += b >> 2
print("a =", a)
print("b =", b)


Output:

a = 4
b = 6

Explanation:

We set the starting values of two variables, a and b, to 3 and 6, respectively. In the code, we right shift the value of b by two bits, add the result to variable ‘a’, and put the final result in variable ‘a’.

Therefore the final output is :

a=4 and b=6

Example2:

a = 3
b = 6
# Left shift by 1 bit
a += b << 1
print("a =", a)
print("b =", b)


Output:

a = 15
b = 6

#### Conclusion

This is about the Python ‘+=’ operator and its numerous implementations.