字符串内置的函数

 a ='studesnt'
print(a.capitalize())
print(a.count('s'))

#字符串的位置查找返回的下标中，字符串的第一个字符的下标定义 为0.
print(a.find('n'))
print(a.find('o'))
print (a.index('d'))
print(a.replace('t','d'))

----------------------------------------------------------------------------------------

Studesnt
2
6
-1
3
sdudesnd

 #字符串中的空格是不会去掉的

a =' stud esnt '
print(a.strip())
print(a.strip('t'))
a =' studesnt '
print(a.strip())
print(a.strip('t'))

——————————————————————————————————————————————————————————

stud esnt
 stud esnt
studesnt
 studesnt #未实现，原因不明

 a =' studesnt '
print(a.isalnum())

————————————————————————————————————————————

False