Python data type conversion
Conversion between strings and numbers
| primitive type | target type | function | example |
|---|---|---|---|
| integer | string | str | str(123)=>“123” |
| floating point | string | str | str(3.14)=>“3.14” |
| string | integer | int | int("123")=>123 int(3.14)=>report error |
| string | floating point | float | float("3.14")=>3.14 float("314")=>314.0 Other types report an error |
Conversion between strings and lists
| primitive type | target type | function | example | describe |
|---|---|---|---|---|
| string | the list | split(sep,maxsplit) | “p,y,t,h,o,n”.split(“,”)=>[“p”,“y”,“t”,“h”,“o”,“n”] | sep is the cutting rule, the default value is a space, maxsplit is the maximum number of cutting times, the default value is -1, and the return value is a list |
| the list | string | sep.join(list) | “_”.join([“p”,“y”,“t”,“h”])=>“p_y_t_h” | sep is a list tuple collection of non-numeric types for the connection rule list, and a value of numeric type is not acceptable |
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string to list
split(sep,maxsplit) #sep为切割规则 默认值为空格 maxsplit为最大切割几次 默认值为-1 返回值为列表 "p,y,t,h,o,n".split(",")=>["p","y","t","h","o","n"] "p,y,t,h,o,n".split(",",2)=>["p","y","thon"] #切割两次后停止 -
convert list to string
#字符串转列表 列表排序后转字符串 可以实现给字符串排序 "_".join([“p”,"y","t","h"])=>"p_y_t_h" ".".join([“p”,"y","t","h"])=>"p.y.t.h" "".join([“p”,"y","t","h"])=>"pyth" ".".join([1,"y","t","h"])=> #有数字 会报错
Conversion between string and bytes types
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What is the bytes type
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- binary data stream bytes
- A special kind of String (you can use String's built-in methods)
- Add b in front of the string to mark b"string"
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bytes类型可以用字符串的一些方法 但是参数也要是bytes类型 -
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str_value="python" #定义字符串类型 str_bytes=b"python" #定义bytes类型 str_bytes.find(b"p") #传入参数为bytes的才能执行
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String to bytes function
| method name | use |
|---|---|
| encode(encoding=“utf-8”,errors=“strict”) | encoding: encoding format after conversion (ascii, gbk, default utf-8) |
| The return value is bytes | errors: The method when an error occurs (the default is strict, throwing an error directly; ignore: ignore the error) |
- bytes to string (basically the same as above)
| method name | use |
|---|---|
| decode(encoding=“utf-8”,errors=“strict”) | encoding: encoding format after conversion (ascii, gbk, default utf-8) |
| The return value is a string | errors: The method when an error occurs (the default is strict, throwing an error directly; ignore: ignore the error) |
Conversion of lists, sets, and tuples
| primitive type | target type | function | example | return type |
|---|---|---|---|---|
| list list | gather | set | set([1,2,3,]) | set collection |
| list list | tuple | tuple | tuple([1,2,3]) | tuple |
| tuple | gather | set | set((1,2,3)) | gather |
| tuple | the list | list | list((1,2,3)) | the list |
| gather | the list | list | list({1,2,3}) | the list |
| gather | tuple | tuple | tuple({1,2,3}) | tuple |