open a file
open(file path, access mode, encoding=encoding method): Only existing files can be opened, otherwise an error will be reported
Access mode:
r : read only (default)
w : write only (overwrite)
~ open an existing file, create a new file if it does not exist
~w mode will overwrite the contents of the previous file
a : write only (append)
#Open the file in the current directory f = open( ' test.txt ' , ' w ' ,encoding= ' UTF-8 ' ) f.close()
#Open the file in the relative path f = open( ' file/test.txt ' , ' w ' ,encoding= ' UTF-8 ' ) f.close()
#Open the file in the absolute path f = open( ' d://test.txt ' , ' w ' ,encoding= ' UTF-8 ' ) f.close()
write file
write(data) : write a string to the file, create the file if it does not exist
# w mode: [write-only] w mode will overwrite the content in the previous file fw = open( ' file/test.txt ' , ' w ' ,encoding= ' UTF-8 ' ) fw.write( ' hello ' ) fw.close()
# a mode: [append] fa = open( ' test.txt ' , ' a ' ,encoding= ' UTF-8 ' ) fa.write( ' Hello everyone ' ) fa.close()
writelines(data) : Write a sequence of strings (list, tuple) to the file, create the file if it does not exist
f = open('file/test.txt','w',encoding='UTF-8') f.writelines([ ' Zhang San\n ' , ' Li Si\n ' , ' Wang Wu\n ' ]) f.close()
read file
read() : read all
fr = open('file/test.txt','r',encoding='UTF-8') readall = fr.read() print(readall)
readlines() : read all line by line and return each line as a list
fr = open( ' file/test.txt ' , ' r ' ,encoding= ' UTF-8 ' ) #Read all line by line and return each line to a list readlines = fr.readlines() print (readlines)
readline() : read a line, each read starts from the cursor read from the previous line to read the next line
fr = open( ' file/test.txt ' , ' r ' ,encoding= ' UTF-8 ' ) #Read a line, each time the cursor read from the previous line starts to read the next line readline1 = fr.readline () readline2 = fr.readline() print('readline1={},readline2={}'.format(readline1,readline2))