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10 CONDITIONAL STATEMENTS

Chapter Outline

10.1 Flow of Control in a Program 10.2 Types of Statements in Python
10.3 Conditional Statements

Introduction
So far, we have developed programs comprising Python statements that are executed in a sequence, one after the
other. However, while solving a real-world problem, a statement may or may not be executed depending on some
condition. For example, while moderating the results in an examination, we may add one or two marks to the marks
obtained by a student if they are failing by a margin of one or two marks, but leave the marks unchanged in all other
cases.
When we execute a program, the order of execution of statements is in the same order as given in the program. This
is the sequential flow of control in a program. However, a program may not always have a sequential flow. Sometimes,
the execution of instructions depends on certain conditions. A set of statements may be executed multiple times or
may not be executed even once.

10.1 Flow of Control in a Program

Depending on how the statements in a program are executed, the flow of control in a program can be broadly classified
into three types:
• Sequential Flow
• Conditional Flow

• Iterative Flow

10.1.1 Sequential Flow
In a sequential flow, the statements are executed sequentially, one after the other. The linear execution of the program
begins with the first statement of the program, continues with the rest of the statements in the same sequence as they
appear in the program, and ends with the execution of the last statement.

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