Python字串和其常用函數合集

# coding:utf-8

if __name__ == '__main__':
    '''
     通過單引號定義
     通過三個單引號定義
     通過三個雙引號定義
    '''

    a = 'this is string'
    b = '''this is string'''
    c = """this is string"""
    print(a, b, c)

# coding:utf-8

if __name__ == '__main__':
    '''
    string.capitalize() 將字串首字母大寫
    '''
    a = 'i am xieruixiang'
    print(a.capitalize())  # I am xieruixiang

# coding:utf-8

if __name__ == '__main__':
    '''
    string.upper() 將字串中所有字母大寫
    '''
    a = 'i am xieruixiang'
    print(a.upper())  # I AM XIERUIXIANG

# coding:utf-8

if __name__ == '__main__':
    '''
    string.lower(),string.casefold() 都能將字串中所有字母小寫
    casefold是lower的加強版
    '''
    a = 'I AM XIERUIXIANG'
    print(a.lower())  # i am xieruixiang
    print(a.casefold())  # i am xieruixiang

# coding:utf-8

if __name__ == '__main__':
    '''
    string.swapcase() 能將字串中的大寫變小寫，小寫變大寫。兩極反轉
    '''
    a = 'i AM xIErUIxIANG'
    print(a.swapcase())  # I am XieRuiXiang

# coding:utf-8

if __name__ == '__main__':
    '''
    string.zfill(width) 用0填充字串到指定width長度，如果字串長度大於等於width則不填充
    '''
    a = 'abcdef'
    print(a.zfill(6))  # abcdef
    print(a.zfill(10))  # 0000abcdef

# coding:utf-8

if __name__ == '__main__':
    '''
    string.count(item) 統計字串中有幾個item
    '''
    a = 'abaacdef'
    print(a.count('a'))  # 3
    print(a.count('aa'))  # 1
    print(a.count('ha'))  # 0

# coding:utf-8

if __name__ == '__main__':
    '''
    string.startswith(item) 判斷字串是否以item開頭
    string.endswith(item) 判斷字串是否以item結尾
    '''
    a = 'abaacdef'
    print(a.startswith('ab'))  # True
    print(a.endswith('ef'))  # False

# coding:utf-8

if __name__ == '__main__':
    '''
    string.find(item) 和 string.index(item) 都是查詢item在字串中第一次出現的位置
    string.find()找不到返回 -1
    string.index() 找不到返回錯誤
    所以使用string.find() 更多
    '''
    a = 'abcedefg'
    print(a.find('c'))  # 2
    print(a.index('c'))  # 2
    print(a.find('ac'))  # -1

# coding:utf-8

if __name__ == '__main__':
    '''
   zstring.strip(char) 過濾字元。char為None則過濾等價空格的字元，否則過濾char字元，從左往右過濾一邊，從右往左再過濾一遍
    string.lstrip(char) 和strip() 相同，只不過該函數只從左往右過濾一遍
    string.rstrip(char) 和strip() 相同，只不過該函數只從右往左過濾一遍
    '''
    a = ' abcdefgh '
    b = '    abcdefgh     '
    c = 'aabbaa'
    print(a.strip())
    print(b.strip())
    print(c.strip('a'))  # bb
    print(c.lstrip('a'))  # bbaa
    print(c.rstrip('a'))  # aabb

# coding:utf-8

if __name__ == '__main__':
    '''
    string.replace(old,new,max) 將字串中的old字串替換成new字串，替換max個，當max為None時替換全部
    '''
    a = 'abcdcdefg'
    print(a.replace('cd', 'ff'))  # abffffefg
    print(a.replace('cd', 'ff', 1))  # abffcdefg
    print(a.replace('hh', 'ff'))  # abcdcdefg

# coding:utf-8

if __name__ == '__main__':
    '''
    string.isspace() 判斷字串是否僅僅由空格字串構成
    string.istitle() 判斷所有單詞的首字母是否大寫
    string.isupper() 判斷所有英文字母是否大寫
    string.islower() 判斷所有英文字母是否小寫
    '''
    a = '     a    '
    space = '       '
    title = 'I Love You'
    title2 = 'I Love you'
    upper = 'I LOVE YOU'
    upper2 = 'I LOVE You'
    lower = 'i love you'
    lower2 = 'I love you'
    print(space.isspace())  # True
    print(a.isspace())  # False
    print(title.istitle())  # True
    print(title2.istitle())  # False
    print(upper.isupper())  # True
    print(upper2.isupper())  # False
    print(lower.islower())  # True
    print(lower2.islower())  # False

# coding:utf-8

if __name__ == '__main__':

    a = 'abcdefg' 

print(a[::])  # abcdefg
    print(a[0:len(a):1])  # abcdefg

    print(a[::-1])  # gfedcba

  print(a[-2:-1:1])  # f