python修改檔案時,使用w模式會將原本的檔案清空/覆寫。可以先用讀(r)的方式打開,寫到內存中,然後再用寫(w)的方式打開。
替換文字中的taste 為tasting
Yesterday when I was young 昨日当我年少轻狂 The taste of life was sweet 生命的滋味是甜的 As rain upon my tongue
#将文件读取到内存中 with open("./fileread.txt","r",encoding="utf-8") as f: lines = f.readlines() #写的方式打开文件 with open("./fileread.txt","w",encoding="utf-8") as f_w: for line in lines: if "taste" in line: #替换 line = line.replace("taste","tasting") f_w.write(line)
2.全文中搜尋替換或單行替換
#文本内容 Yesterday when I was young 昨日当我年少轻狂 The taste of life was sweet 生命的滋味是甜的 As rain upon my tongue taste taste taste taste
#定义一个函数,带有4个参数 #x 表示要更新的文件名称 #y 表示要被替换的内容 #z 表示 替换后的内容 #s 默认参数为 1 表示只替换第一个匹配到的字符串 # 如果参数为 s = 'g' 则表示全文替换 def string_switch(x,y,z,s=1): with open(x, "r", encoding="utf-8") as f: #readlines以列表的形式将文件读出 lines = f.readlines() with open(x, "w", encoding="utf-8") as f_w: #定义一个数字,用来记录在读取文件时在列表中的位置 n = 0 #默认选项,只替换第一次匹配到的行中的字符串 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 #将剩余的文本内容继续输出 for i in range(n,len(lines)): f_w.write(lines[i]) #全局匹配替换 elif s == 'g': for line in lines: if y in line: line = line.replace(y,z) f_w.write(line)
測試
1)預設參數1,只取代已匹配到的第一行
string_switch("fileread.txt","taste","tasting") #结果 Yesterday when I was young 昨日当我年少轻狂 The tasting of life was sweet 生命的滋味是甜的 As rain upon my tongue taste taste taste taste
2)全域替換
string_switch("fileread.txt","taste","tasting","g") #结果 Yesterday when I was young 昨日当我年少轻狂 The tasting of life was sweet 生命的滋味是甜的 As rain upon my tongue tasting tasting tasting tasting
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