Control Statements:
There are 3 types of control statements:
- Conditional Statements
- if
- if - else
- if - elif - else
- Nested if
- Looping Statements/Iterative Statements
- while
- for
- Jumping Statements/Transfer Statements
- break
- continue
- pass
Conditional Statements
1) if - When the given condition is true, then the block of statements executes
Syntax:
if condition :
statement1
statement2
-
-
Indentation: Indentation is the leading whitespace (spaces or/and tabs) before any statement in Python. Other programming languages often use curly brackets "{ }" for this purpose.
Syntax 2:
if condition :
statement 1
statement 2
statement 3
(Here statement 3 is not in the if statement)
Example:
1) if 10<2 :
2) print("Hello")
3) print("Testing Colleges")
output:
>>> Testing Colleges
2) if-else - When the given condition is true, then it executes if-block statements. if the condition is false then else-block statements will be executed.
Syntax:
if condition :
statements 1
else :
statements 2
(If the condition is true then statement 1 will be executed, if the condition is false then statement 2 will be executed).
Example:
a = 10
if a%2==0 :
print("Even number")
else :
print("Odd number")
Output: Even number
3) if - elif - else
When we have multiple conditions, then we need to give as elif expressions.
Syntax:
if condition 1 :
Statement 1
elif condition 2 :
Statement 2
elif condition 3 :
Statement 3
- - -
else :
Statement
Example:
1) a,b = 10,20
2) if a>b :
3) print("a is big")
4) elif a<b :
5) print("b is big")
6) else :
7) print("a and b both are same")
Output: b is big
4) Nested if - if statement having another if-block, then it can be called Nested if.
Syntax:
if condition 1 :
if condition 2 :
Statement 1
Statement 2
else :
Statement 3
Looping Statement:
1) while loop:
while loop is used to execute a group of statements iteratively until some condition becomes false.
Syntax:
while condition :
statement 1
statement 2
- - -
Example:
1) num = 1
2) while num<5 :
3) print(num)
4) num +=1
Output:
1
2
3
4
Example 2: (infinite loops)
1) i = 1
2) while True :
3) print(i, "Hello")
4) i += 1
2) for loop:
for loop is used to execute some action for every element present in some sequence (it may be a string or collection).
Syntax:
for value in sequence :
statements
- - -
Example:
1) name = "Test"
2) for x in name :
3) print(x)
output:
T
e
s
t
Example 2:
1) names = ["apple", "boy", "cat", 4 , True]
2) for x in names :
3) print(x)
output:
apple
boy
cat
4
True
range() function:
The range() function returns a sequence of numbers, starting from 0 (by default), and increments by 1 (by default), and stops before a specified number.
Syntax:
range(start, stop, step)
Example 1: To print Hello 10 Times
1) for x in range(10) :
2) print(x)
Example 2: To display numbers from 0 to 10
1) for x in range(11) :
2) print(x)
Example 3: To display odd numbers from 10 to 20
1) for x in range(10, 20) :
2) if(x%2!=0) :
3) print(x)
Example 4: To display numbers from 10 to 1 in descending order
1) y = range(10, 0, -1)
2) for x in y :
3) print(x)
Jumping Statements:
1) break:
We can use break statements inside loops to break loop execution based on some condition.
Example:
1) for x in range(10) :
2) if x=5 :
3) print("terminated")
4) break
5) print(x)
output:
0
1
2
3
4
terminated
2) continue:
We can use continue statement to skip current iteration and continue next iteration.
Example: To print even number in the range 0 to 9
1) for x in rang(10) :
2) if x%2==1 :
3) continue
4) print(x)
output:
0
2
4
6
8
3) pass:
pass statement acts as a placeholder statement that does nothing, used to represent an empty block of code or as a temporary placeholder for code that will be added later.
(It is an empty statement, it is null statement and it won't do anything.)
Example:
1) for i in 'hello' :
2) if(i == 'l') :
3) pass
4) else :
5) print(i)
output:
h
e
o
