python常用語法和示例_使用Python中的示例進行輸入和輸出操作

python常用語法和示例

A Program needs to interact with the user to accomplish the desired task; this is done using Input-Output facility. Input means the data entered by the user of the program. In python, we have input() and raw_input ( ) function available for Input.

一個程序需要與用戶交互以完成所需的任務；這是使用輸入輸出功能完成的。輸入是指程序用戶輸入的數據。在python中，我們為Input提供了input()和raw_input()函數。

1)input()函數 (1) input() function)

Syntax:

句法：

    input (expression)

If prompt is present, it is displayed on monitor, after which the user can provide data from keyboard. Input takes whatever is typed from the keyboard and evaluates it. As the input provided is evaluated, it expects valid python expression. If the input provided is not correct then either syntax error or exception is raised by python.

如果出現提示，它將顯示在監視器上，之后用戶可以從鍵盤提供數據。輸入接受從鍵盤輸入的任何內容并對其求值。在評估提供的輸入時，它需要有效的python表達式。如果提供的輸入不正確，則python會引發語法錯誤或異常。

Example 1:

范例1：

# python input operations
# user input 
x = input("Enter any value: ")
# printing value
print("Entered value is: ", x)

Output

輸出量

RUN 1:
Enter any value: 12345
Entered value is:  12345
RUN 2:
Enter any value: IncludeHelp
Entered value is:  IncludeHelp
RUN 3:
Enter any value: Python is a progamming language.
Entered value is:  Python is a progamming language.

Example 2:

范例2：

# python input operations
# just provide a value and entered value prints
print(input())
# provide another value
x = input()
print("Your input is: ", x)
# prompting message for input
val1 = input("Enter a value: ")
val2 = input("Enter another value: ")
val3 = input("Enter another value: ")
# printing values
print("val1 =", val1)
print("val2 =", val2)
print("val3 =", val3)

Output

輸出量

Hello
Hello
I'm Shivang!
Your input is:  I'm Shivang!
Enter a value: 100
Enter another value: 23.45
Enter another value: Helllooooooo
val1 = 100
val2 = 23.45
val3 = Helllooooooo

2)raw_input()函數 (2) raw_input() function)

This input method fairly works in older versions (like 2.x).

此輸入法在較舊的版本(如2.x)中相當有效。

Syntax:

句法：

    raw_input (expression)

If prompt is present, it is displayed on the monitor after which user can provide the data from keyboard. The function takes exactly what is typed from keyboard, convert it to string and then return it to the variable on LHS of '='.

如果出現提示，則它會顯示在監視器上，之后用戶可以通過鍵盤提供數據。該函數將完全采用鍵盤輸入的內容，將其轉換為字符串，然后將其返回到'='的 LHS上的變量。

Example: In interactive mode

示例：在交互模式下

>>>x=raw_input ('Enter your name: ')
Enter your name: ABC

x is a variable which will get the string (ABC), typed by user during the execution of program. Typing of data for the raw_input function is terminated by enter key.

x是一個變量，它將獲取字符串(ABC)，由用戶在程序執行期間鍵入。用enter鍵終止raw_input函數的數據輸入。

We can use raw_input() to enter numeric data also. In that case we typecast, i.e., change the data type using function, the string data accepted from user to appropriate Numeric type.

我們也可以使用raw_input()輸入數字數據。在那種情況下，我們進行類型轉換，即使用函數將數據類型(用戶接受的字符串數據更改為適當的數字類型)。

Example:

例：

>>>y=int(raw_input("Enter your roll no."))
Enter your roll no. 5

It will convert the accepted string i.e., 5 to integer before assigning it to 'y'.

它將接受的字符串(即5)轉換為整數，然后將其分配給“ y”。

print()函數/聲明 (print() function/statement)

print evaluates the expression before printing it on the monitor. Print statement outputs an entire (complete) line and then goes to next line for subsequent output (s). To print more than one item on a single line, comma (,) may be used.

print先計算表達式，然后再將其打印在監視器上。 Print語句輸出整行(完整)，然后轉到下一行以進行后續輸出。要在一行上打印多個項目，可以使用逗號(，)。

Syntax:

句法：

    print (expression/constant/variable)

Example 1:

范例1：

# print() example in Python
# using single quotes
print('Hello!')
print('How are you?')
# using double quotes
print("Hello!")
print("How are you?")
# using triple single quotes
# those can be used to print multiple line string
print('''Hello!''')
print('''How are you?''')
# printing multiline string
print('''Hello... how are you?
Hey! I am good, what about you?
I am good also, thanks.''')

Output

輸出量

Hello!
How are you?
Hello!
How are you?
Hello!
How are you?
Hello... how are you?
Hey! I am good, what about you?
I am good also, thanks.

Example 2:

范例2：

# print() example in Python
# printing values
print("Printing direct values...")
print(10) # printing an integer 
print(10.2345) # printing a float
print([10, 20, 30, 40, 50]) # printing a list
print({10, 20, 30, 40, 50}) # printing a set
# printing variables
a = 10 
b = 10.2345
c = [10, 20, 30, 40, 50]
d = {10, 20, 30, 40, 50}
print("Printing variables...")
print(a)
print(b)
print(c)
print(d)
# printing message with variables
print("Printing message variables...")
print("a = ", a)
print("b = ", b)
print("c = ", c)
print("d = ", d)

Output

輸出量

Printing direct values...
10
10.2345
[10, 20, 30, 40, 50]
{40, 10, 50, 20, 30}
Printing variables...
10
10.2345
[10, 20, 30, 40, 50]
{40, 10, 50, 20, 30}
Printing message variables...
a =  10
b =  10.2345
c =  [10, 20, 30, 40, 50]
d =  {40, 10, 50, 20, 30}