python学习1-字符串数字基本运算以及if条件和while循环

python学习1-字符串数字基本运算以及if条件和while循环

字符串表达形式共四种：

name = "string"
name = 'string'
name = """string"""
name = '''string'''

数字基本运算方式：

a = 39
b = 4

c = a + b
c = a - b
c = a*b
c= a**b #次幂
c = a/b

c = a%b #取余数

c = a//b #取除数

条件判断：

in1 = input('please input the rank:')

print(in1)

if in1 == '1':
    print('hello world!')
elif in1 == '2':
    print('HELLO WORLD!')
elif in1 == '3':
    print('hello world 3')
else:
    print('hello world 4')

上面代码中，通过input输入的数字并没有被python视为数字，而是视为了字符串，故下面在条件判断时需要使用引号将数字引起。

循环判断：

while count < 10:
    print(count)
    count = count + 1

使用循环完成简单的算法：

# output numbers: 1 to 10 without 7
n = 1
while n < 11:
    if n != 7:
        print(n)
    n = n + 1

print('---end---')

# find sum of numbers from 1 to 100
n = 1
sumofn = 0
while n < 101:
    sumofn = sumofn + n
    n = n + 1

print(sumofn)

# find sum of numbers 1-2+3-4+...-100
n = 1
sumofnn = 0
while n < 101:
    if n%2 == 0:
        sumofnn = sumofnn - n
    else:
        sumofnn = sumofnn + n
    n = n + 1
print(sumofnn)