1. 基本操作
website = 'http://www.python.org'
# 字符串是不可變的 元素賦值， 切片賦值都是不可以的
# website[-3:] = 'com'
# website[1] = 'http'
Traceback (most recent call last):
File "c:\Users\87600\Desktop\python_basic_learning\3.using_str\1.test_str.py", line 8, in <module>
website[-3:] = 'com'
TypeError: 'str' object does not support item assignment
2. 字符串基本格式化
2.1 轉(zhuǎn)換說(shuō)明符%s
print('{:=^50}'.format('2.1'))
basic_str = 'hello, %s %s enough for ya?'
value = ('world', 'Hot')
format_str = basic_str % value
print(format_str)
=======================2.1========================
hello, world Hot enough for ya?
2.2 模板字符串
print('{:=^50}'.format('2.2'))
from string import Template
tmpl = Template('Hello, $who! $what enough for ya?')
format_str = tmpl.substitute(who='Mars', what='Dusty')
print(format_str)
=======================2.2========================
Hello, Mars! Dusty enough for ya?
2.3 字符串方法format
# 2.3.1 沒(méi)有名稱
print('{:=^50}'.format('2.3.1'))
format_str = '{}, {} and {}'.format('first', 'second', 'third')
print(format_str)
# 2.3.2 使用索引
print('{:=^50}'.format('2.3.2'))
format_str = '{0}, {1} and {2}'.format('first', 'second', 'third')
print(format_str)
format_str = '{1}, {0} and {2}, {0}'.format('first', 'second', 'third')
print(format_str)
# 2.3.3 使用字段名
print('{:=^50}'.format('2.3.3'))
format_str = '{name}, {value}'.format(name='first', value='second')
print(format_str)
# 2.3.4 直接使用變量值進(jìn)行設(shè)置
print('{:=^50}'.format('2.3.4'))
a = 123456
format_str = f'a={a}'
print(format_str)
======================2.3.1=======================
first, second and third
======================2.3.2=======================
first, second and third
second, first and third, first
======================2.3.3=======================
first, second
======================2.3.4=======================
a=123456
2.4 字符串格式化高級(jí)用法
# 2.4.1 在最后結(jié)果添加花括號(hào)
print('{:=^50}'.format('2.4.1'))
format_str = '{{ hello world }}'.format()
print(format_str)
# 2.4.2 替換字段名
print('{:=^50}'.format('2.4.2'))
format_str = '{foo} {} {bar} {}'.format(1, 2, bar=4, foo=3)
print(format_str)
format_str = '{foo} {1} {bar} {0}'.format(1, 2, bar=4, foo=3)
print(format_str)
# 2.4.3 傳遞列表
print('{:=^50}'.format('2.4.3'))
name = ['wu', 'herry']
format_str = 'Mr {name[1]}'.format(name=name)
print(format_str)
# 2.4.4 傳遞字典
print('{:=^50}'.format('2.4.4'))
temp_dict = {'name': 'Wu'}
format_str = 'Mr {name}'.format(**temp_dict)
print(format_str)
# 2.4.5 傳遞對(duì)象
print('{:=^50}'.format('2.4.5'))
import math
format_str = 'model_name = {mod.__name__}, e = {mod.e}'.format(mod=math)
print(format_str)
# 2.4.6 基本轉(zhuǎn)換
print('{:=^50}'.format('2.4.6'))
# !s !r !a --> str repr ascii
print('{pi!s} {pi!r} {pi!a}'.format(pi=' Π '))
# f 浮點(diǎn)數(shù)
print('{num:f}'.format(num=42))
# b 二進(jìn)制數(shù)
print('{num:b}'.format(num=8))
# o 八進(jìn)制
print('{num:o}'.format(num=8))
# x 十六進(jìn)制
print('{num:x}'.format(num=8))
# e 科學(xué)計(jì)數(shù)法表示小數(shù)
print('{num:e}'.format(num=1.233333333))
# 2.4.7 寬度, 精度和千分位
print('{:=^50}'.format('2.4.7'))
# 使用整數(shù)指定寬度
print('{num:10}'.format(num=3))
# 使用整數(shù)指定精度
print('{num:.10f}'.format(num=3))
# 千分位符
print('{num:,}'.format(num=1000**10))
# 2.4.8 符號(hào),對(duì)齊, 用0填充
print('{:=^50}'.format('2.4.8'))
# 在指定寬度和精度前加特定符
# 用0填充
print('{num:010.3f}'.format(num=65.14))
# 正號(hào)
print('{num:+10.3f}'.format(num=65.14))
# 負(fù)號(hào)
print('{num:-10.3f}'.format(num=-65.14))
# 左對(duì)齊
print('{num:<10.3f}'.format(num=-65.14))
# 右對(duì)齊
print('{num:>10.3f}'.format(num=-65.14))
# 在^前添加填充字符串
print('{num:#^10.3f}'.format(num=-65.14))
# 在符號(hào)說(shuō)明符和寬度之間加上#, 在進(jìn)制前加修飾符
print('{num:#10b}'.format(num=10))
======================2.4.1=======================
{ hello world }
======================2.4.2=======================
3 1 4 2
3 2 4 1
======================2.4.3=======================
Mr herry
======================2.4.4=======================
Mr Wu
======================2.4.5=======================
model_name = math, e = 2.718281828459045
======================2.4.6=======================
Π ' Π ' ' \u03a0 '
42.000000
1000
10
8
1.233333e+00
======================2.4.7=======================
3
3.0000000000
1,000,000,000,000,000,000,000,000,000,000
======================2.4.8=======================
000065.140
+65.140
-65.140
-65.140
-65.140
#-65.140##
0b1010
2.5 例子
print('{:=^50}'.format('2.5'))
width = 35
price_width = 10
item_width = width - price_width
header_fmt = '{{:{}}}{{:>{}}}'.format(item_width, price_width)
fmt = '{{:{}}}{{:>{}.2f}}'.format(item_width, price_width)
print('=' * width)
print(header_fmt)
print(header_fmt.format('Item', 'Price'))
print('=' * width)
print(fmt.format('Apple', 0.4))
print(fmt.format('Pears', 0.5))
print('=' * width)
===================================
{:25}{:>10}
Item Price
===================================
Apple 0.40
Pears 0.50
===================================
3. 字符串方法
# 3.1 center 在兩邊填充的字符
print('3.1'.center(50, '='))
print('a'.center(10, '!'))
# 3.2 find 查找子串
print('3.2'.center(50, '='))
# 返回第一個(gè)字串的起始索引
base_str = 'as a moo, moo like moo'
print(base_str.find('moo'))
# 查找不到 返回-1
print(base_str.find('baby'))
# 指定起點(diǎn)終點(diǎn)
print(base_str.find('moo', 6, -1))
# 3.3 join 合并序列元素
print('3.3'.center(50, '='))
seq = ['1', '2', '3']
print(''.join(seq))
# 不能合并數(shù)字列表
seq = [1, 2, 3]
# print(''.join(seq))
# 3.4 lower 返回字符串小寫(xiě)
print('3.4'.center(50, '='))
print('ABCsdsa'.lower())
# 3.5 title 修改所有詞首的首字母大寫(xiě)
print('3.5'.center(50, '='))
print("This's all, herry".title())
# capwords修正
import string
print(string.capwords("This's all, herry"))
# 3.6 replace 將指定的子字符串替換為另一個(gè)字符串
print('3.6'.center(50, '='))
print('as a moo, moo like moo'.replace('moo', 'boo'))
# 3.7 split 將字符串拆分成序列
print('3.7'.center(50, '='))
print('as a moo, moo like moo'.split(','))
# 3.8 strip 去除字符串開(kāi)頭和末尾的特殊字符
print('3.8'.center(50, '='))
print(' hello, world !!'.strip(' '))
# 3.9 translate 替換單字符
# 創(chuàng)建轉(zhuǎn)換表
table = str.maketrans('cs', 'kz')
# unicode碼點(diǎn)的映射
print(table)
# 修改單字符
print('this is a incredible test'.translate(table))
# 刪除指定字符
table = str.maketrans('cs', 'kz', 'a')
print('this is a incredible test'.translate(table))
=======================3.1========================
!!!!a!!!!!
=======================3.2========================
5
-1
10
=======================3.3========================
123
=======================3.4========================
abcsdsa
=======================3.5========================
This'S All, Herry
This's All, Herry
=======================3.6========================
as a boo, boo like boo
=======================3.7========================
['as a moo', ' moo like moo']
=======================3.8========================
hello, world !!
{99: 107, 115: 122}
thiz iz a inkredible tezt
thiz iz inkredible tezt
