理论与实践

数据输入输出

任务

条件语句

任务

for循环

任务

字符串

任务

while循环

任务

列表

任务

二维数组

任务

字典

任务

集合

任务

函数与递归

任务

课程 2. Conditions

难度：

任务«招聘»

💻 Python

IT公司"FutureTech"正在扩大员工队伍，寻找一名新的Python开发人员。为了加快初选速度，人事部门请你编写一个小型筛选程序。该程序应自动判断候选人是否符合基本标准。

候选人标准：

年龄：25至40岁（含）。
经验：超过2年。
Python知识：必须掌握。

编写一个程序，向用户请求三个值：年龄（整数）、经验年限（整数）和Python知识（字符串'True'或'False'）。程序应分析这些数据并输出结论："候选人符合条件"或"候选人不符合条件"。

输入格式

候选人年龄（整数，int）
工作经验年限（整数，int）
Python知识（字符串，str，取值为'true'或'false'）

输出格式

对候选人的判定（行，字符串）

示例

输入

30
5
True

输出

候选人合适

提示

Nested conditions

You can nest some conditional statements (if) into others to create more complex and multi-level checks. This is useful when the next action depends on several consecutive conditions.

The key point here is the correct indentation (usually 4 spaces), which shows Python which block of code belongs to which condition.

Example:

x = 10

if x > 5:
    print("First check passed: x is greater than 5.")
if x < 20:
        print("Second check passed: x is also less than 20.")
else:
print("Second check failed: x is at least 20.")
else:
print("First check failed: x is less than or equal to 5.")

A useful tip: Try not to create too many nesting levels (3 or more). Deeply embedded code becomes difficult to read and understand. Often, complex nesting can be simplified by using logical operators.

Logical operators

Logical operators in Python are used to combine two or more conditions. They allow you to build complex logic without putting conditions into each other. The main logical operators are and, or and not.

The	Name	Description
`or`	logical "OR"	Returns `True` if at least one condition is true.
`and`	logical "And"	Returns `True` only if both conditions are true.
`not`	logical "NOT" (negation)	Inverts the result: `True` becomes `False` and vice versa.

Examples:

a = 5
b = 7

# and: both conditions must be true
s1 = a > 3 and b < 10  # True and True -> True

# or: at least one condition must be true
s2 = a != 5 or b >= 7  # False or True -> True

# not: inverts the result
s3 = not (a < b)       # not (True) -> False

When using and, the result will be true only if both operands are true. When using or, it is sufficient for at least one of the operands to be true. The not operator turns a lie into the truth and vice versa.

Analysis of a complex example:

a, b, c = 7, 10, 11
# Original expression:
print(not(a > 7 and b <= 10) or c != 17)

# Let's take it step by step:
# 1. a > 7  ->  7 > 7  -> False
# 2. b <= 10 -> 10 <= 10 -> True
# 3. (False and True) -> False
# 4. not(False) -> True
# 5. c != 17 -> 11 != 17 -> True
# 6. True or True -> True
# Result: True

A useful tip: To improve readability and avoid errors in complex expressions, always use parentheses () to explicitly specify the order of calculations, even if you remember the precedence of operators (not has the highest priority, then and, then or).

The ternary operator

The ternary operator is a compact way to write a simple if-else condition that returns a value. It allows you to assign a variable a value depending on the condition, and all this in one line.

Syntax: [value if true] if [condition] else [value if false]

Examples:

x = 10
# If x > 5, result will be 100, otherwise 200
result = 100 if x > 5 else 200
print(result) # Will output: 100

y = 20
# Assign the larger of the two values to the variable z
z = x if x > y else y
print(z) # Outputs: 20

# Assign a text value
result_text = "positive" if x > 0 else "non-positive"
print(result_text) # Outputs: positive

A useful tip: The ternary operator is great for simple assignments. However, if the logic becomes more complicated or if, depending on the condition, you need to perform different actions (rather than just return a value), it is better to use a full-fledged if-else construct to preserve the readability of the code.

One-line conditions

If the condition body (if, elif, or else) consists of only one instruction, Python allows you to write it in the same line after the colon.

Example:

x = 10
if x > 5: print("x is greater than 5")

Important style note: Although this notation is syntactically correct, it is often not recommended by the Python Code Style Guide (PEP 8). Placing instructions on a separate line with indentation improves readability and is a generally accepted standard. Use a one-line entry with care, mostly for very simple and obvious actions.

main.py

测试 1

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测试 9

测试 10

开发者解答

# Запрашиваем у пользователя возраст и сразу преобразуем введенную строку в целое число
age = int(input())

# Запрашиваем опыт работы и также преобразуем в целое число
experience = int(input())

# Запрашиваем знание Python. Ввод останется строкой ('True' или 'False')
python_knowledge_str = input()

# Проверяем все условия одновременно с помощью логического оператора 'and'
# 1. Возраст должен быть больше или равен 25 И меньше или равен 40
# 2. Опыт должен быть строго больше 2
# 3. Строка со знанием Python должна быть в точности 'True'
if age >= 25 and age <= 40 and experience > 2 and python_knowledge_str == 'True':
    # Если все три условия выполнены, выводим положительный вердикт
    print("Кандидат подходит")
else:
    # Если хотя бы одно из условий не выполнено, выводим отрицательный вердикт
    print("Кандидат не подходит")