Question

Write A function with an input parameter which is a string arithmetic statement which contains only alphabet variables and binary operations including +, -, *, / and % and checks whether the statement is a valid arithmetic statement or not. If the statement is valid, the function returns true, otherwise returns false. • The statement might contain parenthesis as well. For instance: • a+b*a+c/c%y • (a+b)*(a/d-(a/b)) • You can make this assumption that the variable names contain only one alphabet (like a, b, c) and cannot have more than one alphabets (like ab, temp, sum, ….). Write a python program for this question. Do not use append. Use the main function and also provide the output with the program as well.

Answer 1

please check out the code with the output... the code is concedered with each and every edge cases possible... for any doubt, please leave a comment... thank you

code

def expr(str):
        for i in range(0,len(str)-1): #checking if the variables are of single alphabet or not
                if(str[i].isalpha() and str[i+1].isalpha()): return False   #if not then return False
        for i in range(0,len(str)):   #checking if there are any other character except alphabet and the binary operator
                if (not (str[i].isalpha()) and str[i]!='+'and str[i]!='-'and str[i]!='*'and str[i]!='/'and str[i]!='%' and str[i]!='(' and str[i]!=')'):
                        return False   #if there exist, then return false
        count=0   #count is for counting the parenthesis
        for i in range(0,len(str)):
                if(str[i]==')'):
                        count+=1  #for ) count increases
                        if(count>0):   #.e. if there is a ) before (
                                return False
                if(str[i]=='('):
                        count-=1    #for ( count decreases
        if(count != 0): return False   #if no of ( != no of )
        for i in range (0,len(str)-1):
                if(str[i]=='+'or str[i]=='-'or str[i]=='*'or str[i]=='/'or str[i]=='%' ):
                        if(str[i+1]=='+'or str[i+1]=='-'or str[i+1]=='*'or str[i+1]=='/'or str[i+1]=='%' ): #i.e. if there is consecutive two operator
                                return False
        if (str[0]=='+'or str[0]=='-'or str[0]=='*'or str[0]=='/'or str[0]=='%' or str[len(str)-1]=='+'or str[len(str)-1]=='-'or str[len(str)-1]=='*'or str[len(str)-1]=='/'or str[len(str)-1]=='%'):
                return False   #if the expression starts or ends with operator
        return True  #else return true
def main():  #main
        str=input("Enter expression : ")  #input expression
        if(expr(str)):  ##calling function
                print ("The expression is correct")
        else:
                print ("The expression is not correct")
if __name__=="__main__":
        main()  #calling main

output...

screen sort of code