python字符串 常用函数 格式化字符串 字符串替换 制表符 换行符 删除空白 国际货币格式

# 字符串常用函数
# 转大写
print('bmw'.upper()) # BMW
# 转小写
print('BMW'.lower())  # bmw
# 首字母大写
print('how aae you ?'.capitalize())   # How aae you ?
# 设置每个单次首字母大写
print('michael jackson'.title())  # Michael Jackson
# 大写转小写 小写的转大写
print('abcDEF'.swapcase()) # ABCdef

# 字符串格式化
str1 = '{} {} you'.format('i','love')
print(str1) # i love you
# 索引 组合字符串
str2 = '{2}.{1}.{0}'.format('com','baidu','www') # www.baidu.com
print(str2)

name = 'Eric'
age = 27
height = 180

str3 = '我叫' + name  + ',今年' + str(age)  + '岁，身高' + str(height)
print(str3)
str4 = "我叫{},今年{}岁,身高{}".format(name,age,height)
print(str4)
# 推荐方法
str5 = "我叫{name},今年{age}岁,身高{height}".format( name = name,age = age, height = height)
print(str5)


# 格式化数字
num = 1234567.890134
# 保留两位小数
num1 = format(num, '0.2f')
# 1234567.89
print(num1)
# 保留4位小数
num1 = format(num, '0.4f')
# 1234567.8901
print(num1)

# 国际货币格式
account = '8892343'
amt = 123456789.123
amt1 = format(amt,',')
# 123,456,789
print(amt1)

amt2 = format(amt,'0,.2f')
# 123,456,789.12
print(amt2)

amt3 = "请您向" + account + "账户转账￥" + amt2 + "元"
# 请您向8892343账户转账￥123,456,789.12元
print(amt3)
# 简便写法
amt4 = "请您向{}账户转账￥{:0,.3f}元".format(account,amt)
# 请您向8892343账户转账￥123,456,789.123元
print(amt4)

# 早期字符串格式化
# 我叫张三，今年30岁，体重87.5公斤
name = '张三'
age = 30
weight = 87.5
str6 = "我叫%s, 今年%d岁, 体重%.2f公斤"%(name, age, weight)
# 我叫张三, 今年30岁, 体重87.50公斤
print(str6)

# 制表符 换行符    
 换行
table = '姓名	性别	年龄
赵四	男士	42'
print(table)

#  删除空白
space_str = ' Hello world '
print(space_str)
# 计算长度
len_str = len(space_str);
# 13
print(len_str)

# strip() 删除左右空白  lstrip  删除左边空白  rstrip 删除右边空白
no_space_str = space_str.strip();
print(no_space_str);
# 11
print(len(no_space_str))

# 字符串查找
str7 = 'Nice to meet you, i need you help';
index = str7.find("ee");
#  9  返回字符串第一次出现的索引位置 从0开始计算
print(index)

# find(str,[start],[end])
index2 = str7.find("ee",17);
#  21  返回字符串出现的索引位置 从17开始计算
print(index2)

print('--------------------');
# 判断是否存在
isexist = 'ee' in str7;
#  True / False
print(isexist);


# 字符串替换
# str.replace(原始串，目标串，[替换次数])  默认全部替换
str8 = " this  is  string example...wow!!! this is really string"
pstr8  = str8.replace("is", " was")
# th was   was  string example...wow!!! th was  was really string
print(pstr8)