Question

Suppose user enter this string at terminal

123 456 456 //then hit enter

How do I scan these three (could be more) numbers in different variables in python

Could be something like this:

for i in range(1,n)
    m[i]=#WHAT FUNCTION SHOULD I PUT HERE

In c++ we can easily use cin>>m[i] inside above loop to scan the variables.

If i use input() or raw_input() , they would scan whole line in single variable.

Answer 1

To get a list of these numbers, try

my_list = map(int, raw_input().split())

raw_input() will return the verbatim string as you enter it. The split() method of strings returns a list of strings split at any whitespace character. Finally, the map() invocation turns this list of strings into a list of integers.

If you are using Python 3.x, use input() instead of raw_input().

If you don't want to use a list, and you know the number of input values beforehand, you can use sequence unpacking to assign the values to different varaibles.

a, b, c = map(int, raw_input().split())

will work only if exactly three integers separated by whitespace are entered, and will assigne these three integers to the names a, b and c.

Answer 2

if you do not want to scan the whole input in a list, you can write your own input parser, which reads one character at a time from the input stream:

def nextint(input):
    def skip(input):
        char = input.read(1)
        while str.isspace(char):
            char = input.read(1)
        return char
    char = skip(input)
    while 1:
        result = []        
        while str.isdigit(char):
            result.append(char)
            char = input.read(1)
        yield int(str.join('', result))
        char = skip(input)

now use it like this:

import sys

reader = nextint(sys.stdin)
for value in reader:
    # process the value here
    pass

(the generator will fail on the first block of non-space characters which cannot be converted to int)

Answer 3

In Python 2.x:

m = [int(n) for n in raw_input().split()]

In 3.x:

m = [int(n) for n in input().split()]