控制#

介绍 #

控制功能包括用于控制程序执行时间、程序流程、条件逻辑和项目终止的方法。这些控制功能允许您暂停程序执行、创建循环、定义逻辑路径以及结束程序。以下是可用控制功能的列表，包括方法和核心 Python 关键字：

wait – Pauses execution for a given number of milliseconds or seconds.
for – Repeats code for each item in a sequence.
if – Executes code if a condition is true.
if/else – Runs different code depending on a condition.
if/elif/else – Checks multiple conditions in order.
while – Repeats code while a condition is true.
break – Exits a loop immediately.
stop_project – Ends the running project.
pass – Placeholder used when no action is needed.

等待 #

wait pauses for a specific amount of time before moving to the next method.

Usage:
wait(time, units)

参数	描述
`time`	等待时间，以正整数表示。
`units`	THe unit that represents the wait time: `MSEC` - milliseconds `SECONDS`

参数

描述

time

等待时间，以正整数表示。

units

THe unit that represents the wait time:

MSEC - milliseconds
SECONDS

def main():
    # Turn right for one second, then stop
    drivetrain.turn(RIGHT)
    wait(1, SECONDS)
    drivetrain.stop()

# VR threads — Do not delete
vr_thread(main)

为了 #

for iterates over a sequence (such as a list, tuple, dictionary, set, or string) or any iterable object. It executes the block of code once for each item in the sequence.

使用次数：

for value in expression_list:
    pass

参数	描述
`value`	一个临时变量，用于存储迭代中的当前元素。
`expression_list`	循环遍历的元素集合（例如，列表、字符串、范围）。

def main():
    # Move in a square path
    for index in range(4):
        drivetrain.drive_for(FORWARD, 100, MM)
        drivetrain.turn_for(RIGHT, 90, DEGREES)

# VR threads — Do not delete
vr_thread(main)

def main():
    # Print each item in the list
    colors = ["Red", "Green", "Blue"]

    for color in colors:
        brain.print(color)
        brain.new_line()

# VR threads — Do not delete
vr_thread(main)

如果 #

if executes the indented block of code if the condition evaluates as True.

用法：

if condition:
    pass

参数	描述
`condition`	An expression or variable that is evaluated when the statement runs. If it evaluates as `True`, the code inside the `if` block executes; if it evaluates as `False`, the block is skipped.

def main():
    # Turn right until facing south
    while True:
        if drivetrain.heading(DEGREES) < 180:
            drivetrain.turn_for(RIGHT, 90, DEGREES)
        wait(0.1, SECONDS)

# VR threads — Do not delete
vr_thread(main)

如果/否则 #

if and else determine which indented block of code runs based on whether the condition evaluates as True or False.

用法：

if condition:
    pass
else:
    pass

参数	描述
`condition`	An expression or variable that is evaluated when the statement runs. If it evaluates as `True`, the code inside the `if` block executes; if it evaluates as `False`, the code inside the `else` block executes instead.

def main():
    # Drive after turning around
    while True:
        if drivetrain.rotation(DEGREES) < 180:
            drivetrain.turn_for(RIGHT, 90, DEGREES)
        else:
            drivetrain.drive(FORWARD)
        wait(0.1, SECONDS)

# VR threads — Do not delete
vr_thread(main)

如果/否则 #

The if/elif/else structure selects which indented block of code runs based on conditions:

if runs its block if the condition evaluates as True.
elif checks additional conditions only if all previous conditions evaluated as False. Multiple elif statements can be used.
else runs its block only if none of the previous conditions evaluated as True.

用法：

if condition:
    pass
elif condition:
    pass
else:
    pass

参数	描述
`condition`	An expression or variable that is evaluated when the statement runs. The first condition that evaluates as `True` determines which block executes; if none are `True`, the `else` block runs.

def main():
    # Move depending on the detected color
    while True:
        if front_eye.detect(RED):
            drivetrain.drive(FORWARD)
        elif front_eye.detect(GREEN):
            drivetrain.drive(REVERSE)
        else:
            drivetrain.turn(RIGHT)
        wait(0.1, SECONDS)

# VR threads — Do not delete
vr_thread(main)

尽管 #

while repeatedly runs methods as long as the condition is True. It can also be used like a “Wait until” by adding not to the condition, as shown in the example below.

用法：

while condition:
    pass

参数	描述
`condition`	An expression or variable that is evaluated before each iteration. If it evaluates as `True`, the loop continues; if it evaluates as `False`, the loop stops.

def main():
    while True:
        # Move in a square path forever
        drivetrain.drive_for(FORWARD, 150, MM)
        drivetrain.turn_for(RIGHT, 90, DEGREES)

# VR threads — Do not delete
vr_thread(main)

def main():
    # Wait until an object is detected to stop driving
    drivetrain.drive(FORWARD)
    while not front_distance.found_object():
        wait(50, MSEC)
    drivetrain.stop()

# VR threads — Do not delete
vr_thread(main)

休息 #

break exits a loop immediately.

def main():
    # Stop turning after a button is pressed
    while True:
        drivetrain.turn(RIGHT)
        if front_distance.found_object():
            break
    drivetrain.stop()

# VR threads — Do not delete
vr_thread(main)

停止项目 #

stop_project ends a running project.

Usage:
stop_project()

参数	描述
	此方法没有参数。

def main():
    # Stop the project after a button is pressed
    while True:
        drivetrain.turn(RIGHT)
        if front_distance.found_object():
            stop_program()
        drivetrain.drive(FORWARD)

# VR threads — Do not delete
vr_thread(main)

经过 #

pass is a placeholder for future code and can be used to avoid errors in empty loops, conditionals, and functions.

if condition:
    pass

def function():
    pass