What are loops and conditional statements in Python? Understand them better!
Tags: beginners, programming, python, tutorial
Published: 2022-05-10 18:44:31

With the [basics of python](https://dev.to/wekesa360/python-101-ultimate-python-guide-3ebg), you can now speak the language. in order to get to know and dive in further in to programming and putting some serious logic in code, there are a few things to learn and understand. Let's do it the python way!

- Conditional statements
- Loops

#### Conditional statements
Conditional statements are commands used in handling decisions, in which a decision is made if and only if the pre-stated conditions are either true or false.
For example the traffic lights, you only start driving if and only if the lights turn from red to green else you wait.

Before diving deep into conditional statements there are some logical conditions to consider, of which play a crucial part in making conditions with conditional statements, in python these basic logical conditions from math are:

- Less than, e.g a < b
- Equals, e.g a == b
- Greater than, e.g a > b
- Less than or equal to, e.g a <= b
- Greater than or equal to, e.g a>= b
- Not Equals, e.g a != b

These logical conditions are used with **if statements** and **loops** in manipulating the control flow in programming.

**1. If statement**
A program will only continue to be executed if only the test expression evaluates to true and if the test expression is false, the statements after the condition is not executed.

```
if 2 > 1:
   print("Greater!")
```
Output:
```
Greater
```

**2. Nested if statements**
One condition is executed and if true then the next condition is executed and so on till the last if condition is met. These if statements are declared inside other if statements.

```
n = 10
if n < 20:
   n = 20
   print(" Greater than 10")
   if n < 30:
      n = 30
      print(" Greater than 20")
```
Output: 
```
Greater than 10!
Greater than 20!
```
**3. Elif statements**
*elif* is a keyword that enables a program to go through another if condition if the previous one is false e.g.

```
a = 43
b = 57
if a == 57:
   print("a is equal to 57!")
elif b == 57:
   print("b is equal to 57!")
else:
   print("Sorry, neither a nor b is equal to 57!")
```

Output:
```
b is equal to 57!
```

**4. If not Statements**
*not* is a keyword that returns True if the statement is not true. returns true if  a value is false;
```
num_list = [2,4,6,8,9]
num = 5
if num not in num_list:
   print("num not in num_list")
else:
   print("Found it in num_list!")
```

Output:

```
num not in num_list
```

#### Python loops

A loop is basically a set of instructions or statements of a given program that is repeated a finite number of times until a certain condition is met.
There are two types of loops in python:

 - For loops
 - while loops

**1. for loops**
A for loop is used for iterating over a sequence of statements multiple times, e.g a list, dictionary or a tuple.

```
instruments = ["Guitar", "Piano", "Flute", "Drums"]
for instrument in instruments:
   print(instrument)
```

Output:

```
Guitar
Piano
Flute
Drums
```

**2. while loops**
While loops repeat a statement or a block of statements until a given condition is false. It checks the condition before executing the loop body, if the condition is true, it will go on until it is false, then exit the loop.

```
i = 1
while i != 5:
  print(i)
  i += 1
```

Output:

```
1
2
3
4
```

**Break statement**
A break statement is used in stopping a loop even if the condition still passes as true.

```
i = 1
while i != 8:
  print(i)
  if i == 6:
    break
  i += 1
```

Output:
```
1
2
3
4
5
6
```

**Continue statement**
The *continue* keyword can stop the current iteration and continue with the next iteration.

```
i = 0
while i != 8:
  i += 1
  if i == 6:
    continue
  print(i)
```

Output:
```
1
2
3
4
5
7
8
```

With the knowledge of loops and conditional statements. There's more to do with python. As we progress we unleash its potential.
Here is a simple calculator in which we get to implement the conditional statements.

**Simple calculator**

```
print("The simple calculator")
print("===========")
num1 = input("Enter the first value: ")
num2 = input("Enter the second value: ")
print("===========")
print("\n1.Addition\t2.Subtraction\n3.Multiplication\t4.Division")
choice = input("Pick a choice (1,2,3 or 4): ")
num1 = int(num1)
num2 = int(num2)

if choice == "1":
    print( num1 + num2)
elif choice == "2":
    print(num1 - num2)
elif choice == "3":
    print(num1 * num2)
elif choice == "4":
    print(num1 / num2)
else:
    print("invalid option")
```

**Conclusion**
With that, adios! And happy coding. Hope you found this informative.