Python read and write file
1.Python read and write file
fr=open("readfile.txt","r")
fw=open("writefile.txt","w")
print fr.readline()
print fr.tell()
print fr.readlines()
fw.write("===write line===")
fw.close()
fr.seek(0,0) #The first parameter represents the number of bytes, after which a parameter represents the relative position, 0- start, 1- current, 2- end
for line in fr :
print line
print fr.tell()
fr.close()
#File mode
#a :to append mode to open, can only write
#r+,w+,a+ :Read and write mode, the difference is as follows:
#r+ :From the beginning to cover write
#w+ :Clear file after write
#a+ :Append from end
#Text mode plus b is binary mode,Need to use the sturct module pack and unpack
2.Python write binary file
#coding=utf-8
import struct
fb=open("binary.txt","wb+") #First clear file, binary read and write mode
value1=100
value2=200
str1=struct.pack("ii",value1,value2) #Convert any type of data into a specific format string
fb.write(str1)
fb.seek(0,0)
str2=fb.readline()
print struct.unpack("ii",str2) #Convert strings to data in any format
#Format C Type Python
x pad byte no value
c char string of length 1
b signed char integer
B unsigned char integer
h short integer
H unsigned short integer
i int integer
I unsigned int long
l long integer
L unsigned long long
q long long long
Q unsigned long long long
f float float
d double float
s char[] string
p char[] string
P void * integer