s = "hello,I'm Zxf"

print s[0].upper() + s[1:].lower()

def CharLower(s):
    return s[0]+s[1:].lower()

print CharLower('HELLO')

# 自定义前几个字符大写

def StrUpper(s,n=1):
    return s[:n].upper()+s[n:]

print StrUpper('hello',2)
print StrUpper('sunday')
print StrUpper('september')

s = “hello, I’m Zxf” 
print(s.capitalize()) –> Hello i’m zxf