Introduction to If Statement in Python
In programming, a conditional statement is essential for decision making. It helps to determine or choose which code we need to print next and which to skip. “if” statement in python is an effective pre-defined function statement that helps in deciding the statements or operations that need to be executed. “if” statement is used in setting up the direction in which the program needs to go further.
“if” statement works basically on the Boolean conditions “True” & “False”. A given block of code passes when a given “if” condition is True and does not pass or executed when a given condition is false.
“if” condition can also be used on simple mathematical conditions such as Equal (=), Not Equal (! =), Less than (<), Less than or equal to (<=), Greater than (>) Greater than or equal to (>=).
How If Statement Works
“if” statement is primarily used in controlling the direction of our program. It is used in skipping the execution of certain results that we don’t indent to execute.
The basic structure of an “if” statement in python is typing the word “if” (lower case) followed by the condition with a colon at the end of the “if” statement and then a print statement regarding printing our desired output.
Python is case sensitive too so “if” should be in lower case.
Syntax:
if <condition>:
Print <statement>
Python is sensitive to indentation, after the “if” condition, the next line of code is spaced four spaces apart from the start of the statement. Any set of instructions or condition that belongs to the same block of code should be indented. Indentation is unique to the python programming language. Python strictly adheres to indentation; it is developed that way to make the lines of code neat and easily readable.
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Comparing Python If Statement to Other Languages
In C and Java programming curly braces are used in identifying the “if” statement Block and any statement or condition that is outside the braces does not belong to the “if” Block. The statement or operation inside the “if” block is ended with a semi-colon.
if (condition)
{
Print statement or operation;
}
Python, when compared to other languages, is fairly simple and indentation makes the code neat and understandable easily.
After a given “if” condition we can use multiple “if” statements and else statements in python. The condition is true the following statement or operation is executed or if there is alternate statements or operations mention to execute if the condition is false then that statement inside the “if” block is executed or if there is no alternate statement or condition provided to execute when the condition is false then the program will simply jump to execute the next block of code outside the “if” statement.
Example #1
Code:
if 'cat' in ['dog', 'cat', 'horse', 'penguin']:
print('Cat exists')
print('Cat is my favorite pet')
Output:
In example 1, the “if” condition is true since the cat is present inside the list hence both the print statement is executed and printed. The whole of example 1 is a single block of code.
Example #2
Code:
if 'horse' in ('dog', 'cat', 'horse', 'penguin'):
print(‘horse exists')
print(‘horse is a strong animal')
print('Cat is my favorite pet')
Output:
In example 2, the given condition is true and hence both the print statements were executed. The “if” condition is terminated as soon as indenting back, and hence all the three print statements are executed.
We can also use multiple “if” conditions inside the same block provided the statements follow indentation.
Example #3
Code:
if 'horse' in ('dog', 'cat', 'horse', 'penguin'):
print('horse exists')
if 'cat' in ('dog', 'cat', 'sheep'):
print('cat exist')
if 'sheep' not in ('dog', 'cat', 'horse', 'penguin'):
print('sheep does not exist')
Output:
Python also has logical “AND”, “OR”, “NOT” operators,
Code:
a = 4
b = 7
if a > 0 and b > 0:
print('Both are Positive numbers')
if a%2 or b%2:
print('Either of one is even')
if a > 0 and not b < 0:
print("Both are positive")
Output:
If Statement Flow Chart
Syntax of If Statements
Here some of the syntaxes for “if” statement that is implemented on different conditional statements.
Example #1
Example using mathematical conditions.
Code:
x = 10
y = 17
if (x > 0):
print("X is positive")
if (x % 2 ==0):
print("X is even")
if (y!=x):
print("Both are unique")
if (y % 2 != 0):
print("y is odd")
if (x>=11):
print("condition is True")
if (y<=19):
print("True")
Output:
The condition ‘x’ greater than or equal to 11 is false, hence respective print statement is not executed.
Example #2
Example using mathematical operators.
Code:
a = 5
b = 10
c = 115
if a + b <= 99:
print('a & b are two digit numbers')
if a + c <= 99:
print('a & c are two digit numbers')
if a > 0:
print(c/a)
if b > 0:
print(c/b)
if c%b == 0:
print("The numbers are divisible")
if c%a == 0:
print("a is divisible by c")
if a < b < c:
print("The sum is", a + b + c)
Output:
For c % b the remainder is not equal to zero, the condition is false and hence next line is executed.
Conclusion
So, in general, “if ” statement in python is used when there is a need to take a decision on which statement or operation that is needed to be executed and which statements or operation that is needed to skip before execution. The execution works on a true or false logic. All mathematical and logical operators can be used in python “if” statements.
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This is a guide to If Statement in Python. Here we discuss how if statement works, syntax, flowchart, comparison between python if statement and other languages along with different examples and code implementation. You may also look at the following articles to learn more-
