Python學習第十七天

在下這廂有禮了練習

python修改檔案時，使用w模式會將原本的檔案清空/覆蓋。可以先用讀（r）的方式開啟，寫到記憶體中,然後再用寫（w）的方式開啟。

yesterday when i was young 昨日當我年少輕狂 the taste of life was sweet 生命的滋味是甜的

as rain upon my tongue

#將檔案讀取到記憶體中
with open("./fileread.txt","r",encoding="utf-8") as f:
lines = f.readlines() 
#寫的方式開啟檔案
with open("./fileread.txt","w",encoding="utf-8") as f_w:
for line in lines:
if "taste" in line:
#替換line = line.replace("taste","tasting")
f_w.write(line)

2.全文中搜尋替換或者單行替換

#文字內容 yesterday when i was young 昨日當我年少輕狂 the taste of life was sweet 生命的滋味是甜的 as rain upon my tongue taste taste taste

taste

#定義乙個函式，帶有4個引數
#x 表示要更新的檔名稱
#y 表示要被替換的內容
#z 表示 替換後的內容
#s 預設引數為 1 表示只替換第乙個匹配到的字串
# 如果引數為 s = 'g' 則表示全文替換
def string_switch(x,y,z,s=1):
with open(x, "r", encoding="utf-8") as f:
#readlines以列表的形式將檔案讀出
lines = f.readlines()
with open(x, "w", encoding="utf-8") as f_w:
#定義乙個數字，用來記錄在讀取檔案時在列表中的位置
n = 0
#預設選項，只替換第一次匹配到的行中的字串
if s == 1:
for line in lines:
if y in line:
line = line.replace(y,z)
f_w.write(line)
n += 1
break
f_w.write(line)
n += 1
#將剩餘的文字內容繼續輸出
for i in range(n,len(lines)):
f_w.write(lines[i])
#全域性匹配替換
elif s == 'g':
for line in lines:
if y in line:
line = line.replace(y,z)
f_w.write(line)

測試1)預設引數 1，只替換匹配到的第一行

string_switch("fileread.txt","taste","tasting") #結果yesterday when i was young 昨日當我年少輕狂 the tasting of life was sweet 生命的滋味是甜的 as rain upon my tongue taste taste taste

taste

2)全域性替換

string_switch("fileread.txt","taste","tasting","g") #結果yesterday when i was young 昨日當我年少輕狂 the tasting of life was sweet 生命的滋味是甜的 as rain upon my tongue tasting tasting tasting

tasting

Python學習第十七天

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Python學習 第十七天

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Python學習第十七天