How to use the raw_input() function to obtain user input in Python 2.x

How to use the raw_input() function to obtain user input in Python 2.x

In the Python 2.x version, we can use the raw_input() function to obtain user input. This function reads user input from standard input (usually the keyboard) and returns it as a string. Let's look at some examples of using the raw_input() function.

1. Basic usage

To obtain user input, we only need to call the raw_input() function and save its return value to a variable. For example, the following code will prompt the user to enter a name and save the entered name to the variable name:

name = raw_input("请输入您的姓名：")
print("你好，" + name)

In the above code, we pass in a prompt information as a parameter in the raw_input() function, which Will be displayed on the screen as the user types. After the user completes input, it returns the input as a string and saves it to the variable name. Then we use the print() function to output a greeting, which uses string concatenation to connect the input name and the fixed greeting.

2. Type conversion

It should be noted that no matter what the user inputs, the raw_input() function will return it as a string. If we need to convert user input into other types, such as integers or floating point numbers, we need to use the corresponding type conversion function.

The following is an example, calling the int() function to convert the user input into an integer:

age = raw_input("请输入您的年龄：")
age = int(age)  # 将字符串转换为整数
if age >= 18:
    print("您已经成年了")
else:
    print("您还未成年")

In the above code, we first call the raw_input() function to obtain the user input age and save it in the variable age. Then use the int() function to convert the type of age from string to integer. Finally, according to the user's age, the corresponding information is output.

It should be noted that if the string entered by the user cannot be converted into an integer, it will cause the program to throw a ValueError exception. To avoid this, we can use try-except statement to handle exceptions.

try:
    age = int(raw_input("请输入您的年龄："))
    if age >= 18:
        print("您已经成年了")
    else:
        print("您还未成年")
except ValueError:
    print("请输入一个有效的年龄")

In the above code, we will try to convert the user input into an integer and make the judgment directly in the try statement. If the conversion is successful, the corresponding information will be output; if the conversion fails, that is, the user input cannot be converted to an integer, a ValueError exception will be thrown. We can capture and handle the exception in the except statement and output prompt information.

To sum up, using the raw_input() function can easily obtain user input, but you need to pay attention to the issue of type conversion. When using it, we can reasonably perform input prompts, type conversions and exception handling according to needs to meet the requirements of the program. For users of Python 2.x versions, the raw_input() function is a very useful input function.

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