human
Give me a code to evaluate an array expression with numbers , + and and the other steps required given the following:
Evaluate an array expression with numbers , + and | Function to find the sum of given array.
if string is empty.
stoi function to convert string into integer.
stoi function to convert string into integer.
Find operator.
If operator is equal to ' + ' , add value in sum variable else subtract.
Driver Function"
How can the above be solved in Python?
assistant
#Here is code to evaluate an array expression with numbers , + and and the other steps required.
 def calculateSum ( arr , n ) :
	if ( n == 0 ) :
		return 0
	s = arr [ 0 ]
	value = int ( s )
	sum = value
	for i in range ( 2 , n , 2 ) :
		s = arr [ i ]
		value = int ( s )
		operation = arr [ i - 1 ] [ 0 ]
		if ( operation == ' + ' ) :
			sum += value
		else :
			sum -= value
	return sum
arr = [ "3" , " + " , "4" , " - " , "7" , " + " , "13" ]
n = len ( arr )
print ( calculateSum ( arr , n ) )