if
Since there are no brackets like in Java, indentation is very important in the if statement.
In the example below, you must convert the string type 'n' to an integer.
n = input('Insert an integer.')
print(type(n))
n = int(n)
if n>=0 :
print(n, 'is a positive number.')
if n<0:
print(n, 'is a negative number.')
if ~ else with try~ except
try:
n = int(input('Insert an integer.'))
if n >= 0:
print(n, 'is a positive number.')
else:
print(n, 'is a negative number.')
except:
print('Please insert numbers only.')
if ~ elif ~ else
In Java, there is else if, whereas in Python it is elif.
s = int(input('Insert your score.'))
if s >= 90:
print('A')
elif s >= 80:
print('B')
elif s >= 70:
print('C')
elif s >= 60:
print('C')
else:
print('F')
Loops: for / while
There is no do ~ while statement in Python. Usually for loops are used a lot.
for loop
for loops are many times used with range() built-in function.
Please refer to my last post if you want to know more about the range() function.
링크
Example1
for i in range(10):
print(i+1, 'Cofee and Tea')
for i in range(1, 11):
print(i, 'Love in Life')
for i in range(1, 11, 1):
print(i, 'Happy days')
Example2
for i in range(1, 10, 2):
print(i, end=' ')
print()
for i in range(1, 10):
print(i, end=' ')
print()
for i in range(10):
print(i, end=' ')
print()
for i in range(10, 1, -1):
print(i, end=' ')
Example3
sum = 0
for i in range(1, 11):
sum = sum + i
print('1~',i,'=',sum)
print('sum=', sum)
Example4
odd = 0
for i in range(1, 101, 2):
odd += i
print(odd)
even = 0
for i in range(0, 101, 2):
even += i
print(even);
Example5
It is the same result as Example4, but it is a simpler way with just one for loop.
odd = even = 0
for i in range(1, 101):
if i%2 == 0:
even += i
else:
odd += i
print('1~100 sum of odd numbers:', odd)
print('1~100 sum of even numbers:', even)
Example6
dan = int(input('Insert a number between 1 and 9.'))
print('[',dan,'Table ]')
for i in range(1, 10):
print('{0} * {1} = {2}'.format(dan, i, dan*i))
Example7
for loop with list
list = ['China', 'Canada', 'Egypt', 'South Korea', 'France']
print(type(list))
print(list)
print(list[0])
for i in list:
print(i, end=' ')
print()
for loop with tuple
t = ('red','orange','yellow','green','blue','navy','purple')
print(type(t))
print(t)
print(t[0])
for i in t:
print(i, end=' ')
print()
for loop with dictionary
dic = {'Apple' : 'http://www.apple.com',
'Google' : 'http://www.google.com',
'Naver' : 'http://www.naver.com'}
print(type(dic))
print(dic)
print(dic['Apple'])
for k, v in dic.items():
print(k,':', v)
while loop
while loop is very similar to Java.
Example1
i = 1
while i <= 10 :
print(i,'I love Python')
i += 1
Example2
i=1; odd=even=0
while i <= 100:
if i%2 == 0:
even += i
else:
odd += i
i += 1
print('1~100 sum of odd numbers:', odd)
print('1~100 sum of even numbers:', even)
Example3
Multiplication table with format function.
dan = int(input('Insert a number between 1 to 9'))
i = 1
while i <= 9:
print('{0} * {1} = {2}'.format(dan, i, dan*i))
i += 1
Example4
Multiplication table
dan=2
while dan <= 9:
print('[',dan,'Table ]')
i = 1
while i <= 9:
print(dan, '*', i, '=', dan*i)
i += 1
dan += 1
print()
break and continue
Infinite loop
i=1
while True:
print(i, 'Infinite loop')
i += 1
Infinite loop with break
i=1
while True:
print(i, 'Infinite loop')
if i == 100: break
i += 1
for, if, and break
for i in range(1, 1001):
print(i,'Print')
if i==100:
print('Loop Escaped')
break
continue
continue is for going back to the loop.
Example1
for i in range(1, 11):
if i==5:
continue
print(i, 'Print')
Example2
If it is not divided into 5, it skips printing.
for i in range(1, 101):
if i%5 != 0:
continue
print(i)
