def string_to_float(str):

return float(str)

if __name__ == '__main__':

str = '3.1415926'

res = string_to_float(str)

print(res + 1)

fromfunctoolsimportreduce
 
defstr2float(s):
 returnreduce(lambdax,y:x+int2dec(y),map(str2int,s.split('.')))
defchar2num(s):
 return{'0':0,'1':1,'2':2,'3':3,'4':4,'5':5,'6':6,'7':7,'8':8,'9':9}[s]
defstr2int(s):
 returnreduce(lambdax,y:x*10+y,map(char2num,s))
defintLen(i):
 returnlen('%d'%i)
defint2dec(i):
 returni/(10**intLen(i))
  
print(str2float('123.456'))