字符串格式化#

介绍#

The .format() method in Python is used to create strings that include variables, expressions, or values. This method replaces curly brace placeholders {} in a string with values provided inside .format().

x = 1
y = 5

# Display the variables using .format()
brain.screen.print("Position: ({}, {})".format(x, y))


# Display a calculation using .format()
brain.screen.print("Sum: {}".format(5 + 3))


# Display the robot's battery capacity using .format()
brain.screen.print("Battery: {}%".format(brain.battery.capacity()))

Formatting Numbers with .format – Insert values and expressions into a string.

  • :.xf – 设置要显示的小数位数。

  • round – 将数字四舍五入到给定的小数位数。

  • :, – 添加逗号作为千位分隔符。

  • :.x% – 将小数转换为具有 x 位小数的百分比。

  • :#x – 将数字格式化为十六进制。

  • :b – 将数字格式化为二进制。

颜色——更改控制台中文本的颜色

  • Colors – 设置控制台的文本颜色。

组合字符串——组合文本和值。

  • .format() – 将字符串和变量组合在一个表达式中。

  • + 运算符 – 使用可选的类型转换手动连接字符串。

字符串方法——更改文本的大小写。

  • upper() – 将所有字符转换为大写。

  • lower() – 将所有字符转换为小写。

检查子字符串——测试文本的存在或位置。

  • in – 检查字符串中是否存在某个单词。

  • startswith() – 检查字符串是否以给定值开头。

  • endswith() – 检查字符串是否以给定值结尾。

转义序列 – 使用特殊字符格式化输出。

  • \n – 添加换行符（新行）。

  • \t – 在项目之间添加制表符空格。

Formatting Numbers with .format#

.format can be used to control how numbers appear, including decimal places, rounding, and other formatting styles such as:

Fixed Decimal Places#

.xf controls how many decimal places a number is displayed with.

Usage:
.xf

参数

描述

x

要显示的小数位数。

 
# Display pi with 2 decimal places
pi = 3.1415926535
brain.screen.print("Pi: {:.2f}".format(pi))
# Output: Pi: 3.14

Rounding Numbers#

round rounds a number to a specific number of decimal places before formatting.

Usage:
round(number, x)

参数

描述

number

要舍入的数字。

x

要四舍五入的小数位数。

 
# Display a value rounded to only 2 decimal places
value = 5.6789
brain.screen.print("Rounded: {}".format(round(value, 2)))
# Output: Rounded: 5.68

Thousands Separator#

:, inserts commas as thousands separators to make large numbers more readable.

Usage:
:,

参数

描述

此格式说明符没有参数。

 
# Display a large number separated with commas
number = 1234567
brain.screen.print("Formatted: ")
brain.screen.next_row()
brain.screen.print("{:,}".format(number))
# Output: Formatted: 1,234,567

Percentage#

:.x% formats decimal values as percentages.

Usage:
:.x%

参数

描述

x

要显示的小数位数。

 
# Display a converted decimal to a percentage
value = 0.875
brain.screen.print("Score: {:.1%}".format(value))
# Output: Score: 87.5%

Hexadecimal#

:#x converts numbers to hexadecimal.

Usage:
:#x

参数

描述

此格式说明符没有参数。

 
# Convert 255 to hexadecimal
number = 255
brain.screen.print("Hex: {:#x}".format(number))
# Output: Hex: 0xff

Binary#

:b converts numbers to binary (base 2).

Usage:
:b

参数

描述

此格式说明符没有参数。

 
# Convert 3 to binary
brain.screen.print("Binary: {:b}".format(3))
# Output: Binary: 11

颜色#

您可以使用以下颜色代码更改打印到打印控制台时文本的颜色：

  • [31m – Red

  • [32m – Green

  • [34m – Blue

  • [30m – Black

  • [37m – White

  • [33m – Yellow

  • [91m – Orange

  • [35m – Purple

  • [36m – Cyan

  • [97m – Transparent

All color codes need to follow an escape sequence = \033 in order to function.

You can use this directly in a print command with a string.

# Print VEXcode in Red to the Print Console
print("\033[31mVEXcode")

You can also use it on its own to set all print commands afterwards to the set color.

# Set the Print Console text color to Red before printing
print("\033[31m")
print("VEXcode")

组合字符串#

您可以使用两种方法来组合（或连接）字符串：

Using .format#

Insert values directly into the string using {}.

# Display an answer based on the given emotion
emotion = "good"
brain.screen.print("I'm {}, you?".format(emotion))

+ Operator#

Join multiple parts by using +.

Note: Non-strings must first be converted to strings using str().

# Display the x and y values
x = 10
y = 20
brain.screen.print("X: " + str(x) + ", Y: " + str(y))

字符串方法#

Python 提供了修改和检查字符串的内置方法。

upper#

upper converts all letters in a string to uppercase.

Usage:
upper()

参数

描述

该方法没有参数。

 
message = "vexcode"
brain.screen.print(message.upper())  # Output: VEXCODE

lower#

lower converts all letters in a string to lowercase.

Usage:
lower()

参数

描述

该方法没有参数。

 
message = "VEXCODE"
brain.screen.print(message.lower())  # Output: vexcode

检查子字符串#

in#

in is a keyword that returns a Boolean indicating whether a word exists in a string.

  • True - The word exists in the string.

  • False - The word does not exist in the string.

message = "Hey everyone!"
if "Hey" in message:
    brain.screen.print("Hello!")

startswith#

startswith returns a Boolean indicating whether a string begins with a given value.

  • True - The word starts the string.

  • False - The word does not start the string.

Usage:
startswith(substring)

参数

描述

substring

要在字符串内检查的子字符串。

 
message = "AIM Robot"

if message.startswith("AIM"):
    brain.screen.print("AIM first!")

endswith#

endswith returns a Boolean indicating whether a string ends with a given value.

  • True - The word ends the string.

  • False - The word does not end the string.

Usage:
startswith(substring)

参数

描述

substring

要在字符串内检查的子字符串。

 
message = "AIM Robot"

if message.endswith("Robot"):
    brain.screen.print("Robot last!")

转义序列#

转义序列是字符串中用于格式化文本输出的特殊字符。它们仅适用于控制台。

New Line#

\n moves text to a new line when printing.

# Display text on two lines
print("First line\nSecond line")

Tab Spacing#

\t inserts a tab space between words or numbers,

# Display the quantity of barrels
quantity = 2
print("Barrels:\t", quantity)
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