# 4.2: Functions

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Predefined Functions

General Purpose Functions - functions like print

## Type Conversion

Functions convert variables between data types

int()
float()
bool()
str()


## Methods

### String methods

molecule ="Aspirin is an anti-inflammatory"
print(molecule.capitalize())
print(molecule.replace("in","ins"))
print(molecule.index("r"))
print(molecule.lower())
print(molecule.find('i'))
print(molecule.find('is'))
print('is an' in molecule)

Note, objects are immutable (when you print as capital, it is still lower case.  In the last example we used the "in" operator and it returned a Boolean value (true)

### List Methods

consider the list "molecules" that has aspirin (aspirin is the element of the list you want the index for)

molecule =["aspirin","caffeine","aspirin"]
print(molecule)
print(type(molecule))
print(molecule.index("aspirin"))
print(molecule.count("aspirin"))
molecule.append("acetic acid")
print(molecule)


### Arithmetic Operators

binary operators in the sense that one thing is operating on another.

Operator Precedence is as in normal math

• PEDMAS  (parenthesis, exponents, multiplication, division, addition, subtraction)
• BODMAS: B-Brackets, O-Orders (powers/indices or roots), D-Division, M-Multiplication, A-Addition, S-Subtraction.
print(4+3)
print(4*3)
print(4/3)
print(4//4)
print(4%3)
print(4**3)

7
12
1.3333333333333333
1
1
64


Augmented operators

These are unary operators in the sense that they operate on one thing

x=4
x=x+3
print(x)
x += 3
print(x)
x-=4
print(x)
x/=4
print(x)
7
10
6
1.5


Comparison operators (Boolean Expressions)

x=3>2
print(x)
x=3<2
print(x)
x=3<=2
print(x)
x=3>2
print(x)
x=3 == 2
print(x)
x=3 != 2
print(x)
True
False
False
True
False
True


### Logical Operators

Bolean AND, OR and NOT

molar_mass = 124
print(molar_mass>100 and molar_mass <150)
molar_mass = 124
print(molar_mass<100 and molar_mass >150)
molar_mass = 160
print(molar_mass<100 and molar_mass >150)
molar_mass = 160
print(molar_mass<100 or molar_mass >150)
molar_mass = 124
print(not molar_mass<100)

True
False
False
True
True


### Other operators

#### in (membership operator)

aspirin = 'C9H8O4'

print('H' in aspirin)
print('h' in aspirin)
print('He' in aspirin)
print('N' in aspirin)
print(40*"*")

aspirin_synonyms = [ "aspirin", "Dispril", "Ecotrin", "Polpirin", "Acetylsalicylic Acid"]

print( "Acetylsalicylic Acid" in aspirin_synonyms)
print( "Acid" in aspirin_synonyms)
print( "salicylic Acid" in aspirin_synonyms)
print( "Bufferin" in aspirin_synonyms)
Hello world!

## Compound Statements

humidity = 50
if humidity >= 70:
print("It is a himid day")
elif humidity > 40:
print("It is a nice day")
else:
print("It is an arid")

It is a nice day


4.2: Functions is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.