Code :
n,X=input(),0
for t in range(int(n)):
eval(input())
print(X)
Traceback (most recent call last):
File "prog.py", line 3, in <module>
eval(input())
File "<string>", line 1
X++
^
SyntaxError: unexpected EOF while parsing
Using raw_input instead of input() in the only solution I am able to find but in python 3.x input is raw_input(): How do I use raw_input in Python 3
any other method?
FYI; I am trying to solve: http://codeforces.com/problemset/problem/282/A
Remove the eval() call.
input() in Python 2 is the equivalent of eval(input()) in Python 3, and if you need to use raw_input() in Python 2 then in Python 3 you need to remove the eval() call.
You'll have to parse the input yourself; ++ is not a valid Python operator, you cannot use eval() to solve that Codeforces problem.
The simplest way to solve the posted problem is to read the input line by line:
import sys, itertools
count = int(next(sys.stdin))
x = 0
for line in itertools.islice(sys.stdin, count):
x += 1 if '++' in line else -1
print(x)
Related
I am working on a very basic problem on Hackerrank.
Input format:
First line contains integer N.
Second line contains string S.
Output format:
First line should contain N x 2.
Second line should contain the same string S.
sample test case
5
helloworld
my code is as: (on PYTHON 3)
n=int(input())
s=input()
print(2*n)
print(s)
I am getting error:
Execution failed.
EOFError : EOF when reading a line
Stack Trace:
Traceback (most recent call last):
File "/tmp/143981299/user_code.py", line 1, in <module>
N = int(input())
EOFError: EOF when reading a line
I tried this method to take input many times and this is the first time I am having this error. Can anyone please explain why?
use a try/except block to handle the error
while True:
try:
n=int(input())
s=input()
print(2*n)
print(s)
except:
break
I try to learn this book under python-3 environment but it pops out an error when I try to run it. Is there anywhere to fix this?
Once I deleted
print("Ready, hit RETURN to continue, CTRL-C to abort.")
input()
The code ran perfectly. So I think it should be the syntax problem between python 2 and python 3
from sys import argv
from os.path import exists
script, from_file, to_file = argv
print("Copying from %s to %s" % (from_file,to_file))
# we could do these two on one line too, how?
in_file = open(from_file)
indata = in_file.read()
print("The input file is %d bytes long" % len(indata))
print("Does the output file exist? %r" % exists(to_file))
print("Ready, hit RETURN to continue, CTRL-C to abort.")
input()
out_file = open(to_file, 'w')
out_file.write(indata)
print("Alright, all done")
out_file.close()
in_file.close()
When I try to run it, it should stops at input() and wait me hit the return key to continue. But in reality, the code stopped and an error called
"Traceback (most recent call last):
File "ex17.2.py", line 18, in <module> g
input("")
File "<string>", line 0
^
SyntaxError: unexpected EOF while parsing
popped out.
Yes you are correct!! The error you are getting is due to python version change. This code works perfectly fine in python 3.x but fails in python version under 3.x.
Hope this helps.
Since Python 2's raw_input was changed to just input for Python 3, I was wondering if there was a way to take input while accounting for both Python 2 and 3. I'm trying to write a script for both versions, and this input part is the only thing that's not working well.
I tried running just input with Py2, and this happens:
>>> a = input('Input: ')
inp: test
Traceback (most recent call last):
File "<pyshell#0>", line 1, in <module>
a = input('Input: ')
File "<string>", line 1, in <module>
NameError: name 'test' is not defined
I saw a workaround to quote the input:
>>> a = input('Input: ')
inp: "testing test"
a
'testing test'
Is there a way to concatenate the quote to the beginning and end of the input? '"' + input('input: ') + '"' isn't working
Probably not a good practice, but you can use a try block to test whether the raw_input() is being recognized (thus telling you whether you're on Python 2.x or Python 3.x):
try:
a = raw_input('input: ')
except NameError:
a = input('input: ')
I would use raw_input() to test because it's not accepted by Python 3.x and is what you expect to use in Python 2.x, so the input() will not trigger in Python 2.x.
I'm not an expert so I'm sure there are better suggestions.
#Chris_Rands' suggested dupe thread has a more elegant solution by binding input = raw_input so if you have multiple input(), you only need to try once.
This works for both Python 2 and 3.
from builtins import input
input("Type something safe please: ")
I am learning MPI in python by myself. I just started from the basic documentation of MPI4py. I started with this code:
from mpi4py import MPI
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
if rank == 0:
data = {'a': 7, 'b': 3.14}
comm.send(data, dest=1, tag=11)
elif rank == 1:
data = comm.recv(source=0, tag=11)
When I ran this program, I got following error:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "MPI/Comm.pyx", line 1175, in mpi4py.MPI.Comm.send (src/mpi4py.MPI.c:106424)
File "MPI/msgpickle.pxi", line 211, in mpi4py.MPI.PyMPI_send (src/mpi4py.MPI.c:42120)
mpi4py.MPI.Exception: Invalid rank, error stack:
MPI_Send(174): MPI_Send(buf=0x10e137554, count=25, MPI_BYTE, dest=1, tag=11, MPI_COMM_WORLD) failed
MPI_Send(100): Invalid rank has value 1 but must be nonnegative and less than 1
I didn't find any working solution for this problem. I am using Mac OS X El Capitan.
Thanks in Advance!
The program complains that 1 is not a valid rank for MPI_Send(): it means that your program is running on a single process.
Are you running it by using python main.py ? Try to use mpirun -np 2 python main.py, where 2 is the number of processes. The latter is the usual way to run mpi programs.
Help! end='' is causing a syntax error and I'm not sure why.
def print_game_board(game_board_marker):
for i in range(len(game_board_marker)):
for j in range(len(game_board_marker[i])):
print(str(game_board_marker[i][j]).rjust(4), end='')
print()
print()
It seems like you're using Python 2.x, not 3.x.
Check your python version:
$ python -V
Python 2.7:
>>> print(1, end='')
File "<stdin>", line 1
print(1, end='')
^
SyntaxError: invalid syntax
Python 3.3:
>>> print(1, end='')
1>>>