Open File and Read All Content :

f = open("demofile.txt", "r")
print(f.read())
f.close()

Output :

[Contents of demofile.txt]

Open File Using Full Path and Read :

f = open("D:\\myfiles\\welcome.txt", "r") # Double backslashes in path
print(f.read())
f.close()

Output :

[Contents of welcome.txt]

Read First 5 Characters from File :

f = open("demofile.txt", "r")
print(f.read(5))
f.close()

Output :

[First 5 characters]

Read First Line from File :

f = open("demofile.txt", "r")
print(f.readline())
f.close()

Output :

[First line of file]

Read Two Lines from File :

f = open("demofile.txt", "r")
print(f.readline())
print(f.readline())
f.close()

Output :

[First line]
[Second line]

Loop Through File Line by Line :

f = open("demofile.txt", "r")
for x in f:
    print(x)
f.close()

Output :

[All lines printed one by one]

Close File After Reading One Line :

f = open("demofile.txt", "r")
print(f.readline())
f.close()

Output :

[First line of file]