创建文件并写入字符串

# 创建文件并写入字符串
file = open("cau.txt", 'w')
str = "Hello China Agricultural university!"
file.write(str)
file.close()

文件cau.txt内容：
Hello China Agricultural university!

读文件

# 读文件
with open("cau.txt", 'r') as f:  # 自动关闭文件
    s1 = f.read(10)  # 读取前10个字符
    s2 = f.read()  # 读取剩余字符
    f.seek(0)  # 文件指针回退到文件开头
    s3 = f.read()  # 读取
    print("s1:", s1)
    print("s2:", s2)
    print("s3:",s3)

输出结果：
# s1: Hello Chin
# s2: a Agricultural university!
# s3: Hello China Agricultural university!