Conditional Statements in C Programming

Name: Conditional Statements in C Programming
Author: Mike McMillan

Learn how to store data in variables and how to write and execute statements

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Course: On-Demand

Hi, this is Mike McMillan, and welcome to this lesson on decision making using the simple if statement. In C, the way we make decisions in code is with an if statement. The if statement looks at a relational expression, and then based on that expression, whether the expression's true or false, decides whether or not to perform or execute a statement or more than one statement. So if you look on the screen I've already put a syntax template for a simple if. And so here it is, you have the keyword "if," followed by a relational expression, which is just some expression that involves a Boolean operator, greater than, less than, not equal to, equal to, all those operators. Then, an open curly brace and one or more statements to execute if the expression evaluates to true. If the expression evaluates to false, no statement inside the curly braces is executed. Now, I'm lying to you just a little bit, by saying that the curly braces are required because strictly speaking, for a single statement inside an if, you don't need curly braces. But the convention with programmers these days is to use the curly braces regardless, because it tends to not lead to mistakes, I'm gonna demonstrate what happens that can cause a mistake here in just a moment. So let's take a look. So here I've initialized a variable salary to 20,000. So here's what we're gonna say. So here's an example of a simple if. We check to see if the value of salary is greater than 19,999. If it is, then it's going to say, "You need a raise." Otherwise nothing happens, so watch what happens. We can also take the curly braces off and we still get the correct response. However, if I want to have more than one statement to execute if the relational expression is true, then I have to include the curly braces. So let's put them back. Well, I'll tell you what, let's don't, let's leave them out. And this is why people tend to use curly braces all the time now. And then I wanna also say... So I want the program to say, "You need a raise, I think you deserve 30,000." So watch what happens when we run that. It does do both, okay? But watch, let's change this to make the expression false. Now, I don't want it to say anything, but watch what happens. It still says, "I think you deserve 30,000." That's because without curly braces, only one statement, the statement directly underneath the relational expression is not executed in this case. This statement is executed no matter what. So, by putting curly braces around our if, now nothing is printed because the relational expression was false, and that's what we want. So, the key to writing good if statements is to always use the curly braces even if you don't necessarily need them, and you'll see in all my demonstrations that I always use them. Now, let's wrap up this discussion with a very quick overview of the relational operators. I'll put 'em inside this comment so that you can see them. So we have greater than and greater than or equal to. We have less than, and less than or equal to. We have equal to, which is double equal signs, we've talked about that before. And then we have not equal to, which is exclamation point equal sign. Those are the different relational expressions we can use when writing if statements. So that wraps up this lesson on the simple if, and in my next lesson, we're going to talk about the next version of the if statement, the if else, which will allow us to perform a task if the relational expression turns out to be false.

Beginner Provider : Mike McMillan 4 Lessons · 21m in Arabic, German, English, Spanish, French, Portuguese, Chinese

Course Description

The first skill most programmers learn is how to use variables in their programming language of choice, since computing usually involves working with data. The C language has specific rules for creating and using variables, which might be familiar to programmers who’ve used another language, but can confuse someone who’s brand new to programming. For example, variable names have to start with an alphabetic character and can contain numbers, but not symbols—unlike some of the more popular scripting languages, C variables must be declared before use so the compiler can keep track of the variable’s data type.

These lessons on Conditional Statements discuss how to create and use variables to store data, how to use constants to create unchangeable variables, and how to write arithmetic statements for performing mathematic equations. We’ll also go over declaring variables, assigning data to variables, and combining declaration and storing data into a single statement.

What You'll Learn

Declare variables according to C's rules for creating and using variables
Assign data to variables and combine declaration and storing into a single statement
Use constants to create unchangeable variables
Write arithmetic statements for performing mathematic equations
Write simple if statements and if-else statements
Apply if-else if statements and switch statements

Key Takeaways

In C, variable names must start with an alphabetic character and can contain numbers but not symbols.
C variables must be declared before use so the compiler can keep track of the variable's data type.
Constants are used to create unchangeable variables, while arithmetic statements perform mathematic equations.
The course covers conditional statements including simple if, if-else, if-else if, and switch statements.
Declaring a variable and storing data into it can be combined into a single statement.

Frequently Asked Questions

What does this course cover?

It covers how to create and use variables to store data, how to use constants to create unchangeable variables, how to write arithmetic statements for performing equations, and conditional statements such as simple if, if-else, if-else if, and switch statements.

What will I learn about variables in C?

You will learn how to declare variables, assign data to variables, and combine declaration and storing data into a single statement, following C's specific rules for creating and using variables.

Who is this course suited for?

It is suited for those learning C, including programmers familiar with another language as well as those brand new to programming, since it explains C's specific rules for variables that can confuse newcomers.

What conditional statement topics are included in the lessons?

The lessons cover Simple If Statements, If-Else Statements, If-Else If Statements, and the Switch Statement.

What skills does this course help develop?

It helps develop skills in C and C-based programming languages, conditional compilation, conditional expressions, conditional statements, and interactive C.