P13数字与字符串类型的转换

calculate : You can do math with numbers

the plus sign for addition; the negative sign for subtraction; the slash for division; the asterisk symbol for multiplication; exponent or to the power of is a double asterisk.

first_num=6
second_num=2
print(first_num+second_num)  #8
print(first_num**second_num) #36

type conversion `convert from number to string: When displaying a string that contains numbers you must convert the numbers into strings. call these string function str()

days_in_feb=28
print(str(days_in_feb)+' days in February')

convert from string to number: different data type conversion ,changing from one data type to another.

int(): wil convert it into an integer.(a whole number)

float():wil convert it into a number of floating number or something that might have decimal palces.

first_num=input('enter first number')
second_num=input('enter second number')
print(int(first_num)+int(second_num))
print(float(first_num)+float(second_num))

Number values are used for math operations and to specify individual rows in lists and arrays.

P14实操

如上