python學習7——函數

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1、函數。

def profit(volume, price,cost):    print("We sell %d ice cream a day." % volume)    print("You can buy an ice cream at the price of %d dollars" % price)    print("Make an ice cream will cost us %d dollars." % cost)    print("Then our daily profit can be %d dollars." %((price-cost)*volume))print("We can just give the function numbers directly:" )profit(500,20,10)print("Or we can use variables from our script:")volume = 200price  =10cost  = 3profit(volume,price,cost)

輸出結果：

 2、函數和檔案。

from sys import argvscript, input_file = argvdef print_all(f):　　print(f.read())def rewind(f):　　f.seek(0)def print_a_line(line_count,f):　　print(line_count,f.readline())current_file = open(input_file)print("First let‘s print the whole file:\n")print_all(current_file)print("Now let‘s rewind, kind of like a tape).")rewind(current_file)print("Let‘s print three lines:")current_line = 1print_a_line(current_line,current_file)current_line = current_line+1print_a_line(current_line,current_file)current_line = current_line+1print_a_line(current_line,current_file)

輸出結果：

為了知道+=的作用，我將代碼修改為：

from sys import argvscript, input_file = argvdef print_all(f):　　print(f.read())def rewind(f):　　f.seek(2)def print_a_line(line_count,f):　　print(line_count,f.readline())current_file = open(input_file)print("First let‘s print the whole file:\n")print_all(current_file)print("Now let‘s rewind, kind of like a tape.")rewind(current_file)print("Let‘s print three lines:")current_line = 1print_a_line(current_line,current_file)current_line+= current_line+1print_a_line(current_line,current_file)

輸出結果：

可以看到，第二行的內容沒有被列印出來。

結論：

a+=b 即為 a=a+b

3、return

def add(a,b): print("ADDING %d + %d" % (a,b)) return a+bdef subtract(a,b): print("SUBTRACTING %d-%d" % (a,b)) return (a-b)def multiply(a,b): print ("MULTIPLYING %d * %d"%(a,b)) return (a*b)def divide(a,b): print("DIVIDING %d / %d" %(a,b)) return (a/b)print("Let‘s do some math with just functions!")age = add(30,5)height = subtract(70,4)weight=multiply(90,2)iq = divide(150,2)print("Age: %d, Height: %d, Weight: %d, IQ: %d" %(age,height,weight,iq))print("Here is a puzzle.")what = add(age, subtract(height,multiply(weight, divide(iq,2))))print("That becomes:",what,"\n Can you do it by hand?")

輸出結果：

 

python學習7——函數