Python string formatting

There are two ways to format a Python string, one is in the format string "%", the other is the Format function formatting, the latter how to use I do not know.

Formatting action Symbols

There are several general formatting operators:

%c converted to character (ASCII value, or string of length one)

%r takes precedence over string conversions with the repr () function

%s takes precedence over string conversion with the STR () function

%d/%i turns into signed decimal number

%u turns into unsigned decimal number

%o Turn unsigned octal number

%x/%x turns to unsigned hexadecimal number (x/x represents the case of the converted hexadecimal character)

%e/%e turns into scientific notation (e/e control output e/e)

%f/%f to floating point (fractional part natural truncation)

%g/%g%e and%f/%e and%f abbreviations

Percent output% (the formatted string includes a percent semicolon, so you must use a percentile)

In addition to the format operator, we need to use the Format Operator helper in the process of using string formatting

The General Format operator Helper is as follows:

* Define width or decimal point accuracy

-Used for left alignment

+ Show plus sign (+) in front of positive number

# 0 (0) in front of octal number, "0x" or "0X" before hexadecimal (depending on "x" or "X")

0 The number displayed is preceded by "0" instead of the default space

(Var) mapping variables (typically used to process parameters of a field type)

M.N m is the smallest total width displayed, and n is the number of digits after the decimal point (if available)

I'm familiar with it. Three%s%d%f

Simple conversion Case:

1; #简单转换, the following format character D option is used to format an integer, and if I convert a value here that deals with an integer, an error will be made, such as a string

SS = ' Price of eggs:$%d '% 42

Print (ss)

# #运行结果如下

Price of eggs:$42

2. Add a String

SS = ' Price of eggs:$%d '% "greatly large"

Print (ss)

# #报错信息如下:

Traceback (most recent):

File "d:/pythontest/mypython/day1/str.py", line 5, <module>

SS = ' Price of eggs:$%d '% "greatly large"

TypeError:%d format:a number is required, not str

The rest will be understood later.

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Python string formatting