**Table of Contents**show

**Conditionals**

- Flow of execution of instruction can be controlled using conditional statements
- Conditional statements have some Boolean expression
- Boolean expression can have relational operators or logical operators or both

**Boolean values and Operators**

**Boolean Data type**

- The Boolean data type is either True or False
- In python, Boolean variables are defined by True and False keywords
- In programming, one often need to know if an expression is True of False
- When two values are compared, the expression is evaluated and python returns Boolean answer

**Example**,

```
>>> print(10>9)
True
```

- Any string is True, except empty strings
- Any number is true, except 0
- Any list, tuple, set and dictionary are True, except empty ones

```
>>> bool(1)
True
>>> bool(0)
False
>>> True + True
2
>>> True + False
1
>>> False + False
0
>>> True * False
0
>>> True
True
>>> False
False
>>> bool(9)
True
>>> bool("Hello")
True
>>> bool("")
False
>>> bool(True + True)
True
>>> bool(True * False)
False
```

**Comparison (Relational) Operators**

- Comparison Operators are used to compare values
- It either returns true or false depending on the condition
- Assume a = 3 and b = 2

**Example**

```
a = 3
b = 2
print("a==b = ", a==b)
print("a!=b =",a!=b)
print("a>b =",a>b)
print("a<b =",a<b)
print("a>=b=",a>=b)
print("a<=b = ", a<=b)
```

**Output**

```
('a==b = ', False)
('a!=b =', True)
('a>b =', True)
('a<b =', False)
('a>=b=', True)
('a<=b = ', False)
```

**Logical Operators**

Logical Operators are used to combine conditional statements

**Example**

```
a=5
b=10
print("a<5 and b <20", a<5 and b<20)
print("a<5 or b <20",a<5 or b<20)
print("not(a<5 and b<20)",not(a<5 and b<20))
```

**Output**

```
('a<5 and b <20', False)
('a<5 or b <20', True)
('not(a<5 and b<20)', True)
```

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