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In Python, every piece of data has a definite type. The most common data types are:
str - the string
int - an integer
float - floating point number, that is, decimal
bool - Boolean type, a type used to represent the two logical states of true and false
There are also compound data types, such as:
list - the list
dict - the dictionary
tuple - tuple
Although some data "look" similar, if the type is different, the operations that can be performed are also different.
For example, the input obtained through input is all str string type.
Even if the user enters a number, such as 3, but the program gets a string 3 instead of the number 3, it cannot be directly added to the number 1, otherwise an error will be reported.
If you want to perform mathematical operations on the obtained value, the common solution is to do a type conversion to let the program know that it is a number.
a = input()
a = int(a)
a = a + 1
print(a)Although the data type increases the restriction, it allows the program to match the data with the appropriate operation, reducing the possibility of program error.
Even if some languages do not perform mandatory type checking, the program still needs to store data in a certain format. For example, the character 3 and the number 3 are different data for the computer and cannot be stored in the same way. It's just that these languages will try to convert it into a usable type when using it. This is more flexible during development, but it also hides risks.
A cold knowledge: A well-known small website crashed for 3 hours before because of the misuse of a string 0 and a number 0. (Lua language does not perform mandatory type checks. When b is the character '0' or nan, the program can run normally, but it will not enter if return, so it will fall into an infinite loop)
In addition, it is not that different types must not be combined for calculations. Some calculations are performed between specific types. For example, strings and numbers can be multiplied:
print('3' * 2)result:
33What else do you want to know about types in Python? Welcome to discuss in the message area.
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