C++ If-Else Statement | Syntax, Types & More (+Code Examples)

When incorporating logic into our code, we often need to make decisions based on certain conditions being fulfilled. The results of these logical conditions determine which particular block of code will be executed to get the desired result. We use specific statements for this decision-making process that ultimately control program flow. They are referred to as if-else conditional statements or if-else C++ for short.

In this article, we will examine the different types of decision-making statements in C++ programming. These include simple if statements, if-else statements, nested if, if else, if ladder, and jump statements. So, let’s get started exploring the if-else statement in C++.

Decision Making Statements In C++

In C++ programming language, we have to make decisions on program flow (regarding, say, what to do next) based on the conditions in our problem statement. These decisions help determine the flow and even change the sequential order of execution of a program.

Often, we need to pit possibilities against each other and provide probable control flow options when either of the possibilities comes true. This is where the decision-making and, hence, the conditional/ decision-driven statements come into play in programming.

Take, for example, a simple scenario where a program prints the results for students.

• The students whose marks are 40 or more pass, and those below fail.
• So if the condition of marks greater than or equal to 40 is met, the program will print Pass. Otherwise, it will print fail.

This shows how a simple decision affects the further course of action of a C++ program. In general, using decision-making statements in codes helps the compiler decide the direction or flow of program execution. Let's examine the general syntax followed by most of these if-else C++ statements.

Syntax Of If-Else C++:

if (condition){
// Code to be executed if the condition yields true
}else {
// Code to be executed if the condition yields false
}

Here,

• The if and else keywords mark the two possibilities in our decision-making structure.
• The condition inside braces refers to the conditional logic/ target statement whose outcome will determine which block of code is implemented.
• The curly brackets {} contain the blocks of code to be executed depending upon the result of the logical condition.

Note: The simple if statement does not have the else keyword. We will discuss this in the sections ahead.

The above flowchart gives a general overview of how the decision-making and execution process works when if/ if-else C++ conditional statements are applied.

Types Of Conditional Statements In C++

In C++, several variations and types of if statements can be used to handle different scenarios and conditions. The decision-making statements available in C++ are:

1. If statement
2. If-else statement
3. Nested if statement
4. If-else-if ladder
5. Condition Statement
6. Switch case
7. Jump statements (break, continue, goto, return)

We will discuss each of these types of loop control statements in detail, with the help of code examples, in the section ahead.

If Statement In C++

In C++, the if statement is the simplest form of decision-making statement. It is used to determine whether a block of statements will be executed based on a conditional statement. The condition has only two boolean values/results, i.e., either true or false.

• If the condition in the if statement is true, the code block inside the curly brackets is executed.
• In case the condition evaluates to false, we move to the line of code after the if-block.
• If there are no curly braces {} after the if statement, only the first statement inside the if block is considered.

Syntax-

if (condition){
// conditional code body
}

Here,

• The if keyword marks the beginning/ initiation of the if statement.
• The (condition) refers to the condition we are verifying.
• The curly braces {} contain the conditional code that will be executed if the condition is fulfilled.

How Do If Statements In C++ Work?

The general working mechanism behind the if statement is mentioned below and is also represented in the flow diagram.

A simple if statement in C++ is used to check whether a condition is true or false. Then-

• If the condition is true, the statements inside the if block are executed.
• In case the condition is false, the control goes to the first statement after the if block, and the normal execution of the program continues.

For example, let's say the condition we check in the if statement is a>b for variables a and b.

• If the expression (a>b) is true, then the statements/ code block inside the curly bracket is executed. After the execution of the code block is done, the control is transferred to the statements outside the body of the if statement.
• On the other hand, if the expression (a>b) is false, then the statements/ code inside the curly brackets are ignored. The control is directly passed to the statements outside the body of the if statement.

Now, let's look at a code example that showcases the implementation of an if statement in C++.

Code Example:

Output:

Passed
Happy

Explanation:

In the simple C++ program, we begin by including the essential header file <iostream> and the namespace std.

1. Inside the main() function, which is the entry point of program execution, we declare an integer data type variable marks and assign it a value of 60.
2. Then, we define an if statement to find whether a student has passed or not. The condition uses the greater than relational operator to determine if the marks are greater than 40.
3. If the condition is true, the cout statements inside the code block are executed and the statement is printed to the console.
4. If the condition is false, the code block inside the if-statement will be skipped.
5. After that, we move to the cout statement outside of the statement. The newline escape sequence in the second count statement shifts the cursor to the next line and prints the string- Happy.
6. This clearly shows that if the condition is fulfilled, which it is in this example, then the conditions code is executed.
7. Finally, the program terminates with a return 0 statement indicating successful execution to the operating system.

Here, the if condition is true; hence, the output has both strings, i.e., Passed and Happy. Had the condition not been met, the output would have been the single string Happy. Try to run this C++ program with an integer value of less than 40.

If-Else Statement In C++

The if-else in C++ is the most commonly used decision-making statement. It is used to decide which block of statements will be executed based on the result of the conditional statement. Here also, the condition has only two boolean values, i.e., either true or false.

If the condition is true, the statements inside the if block are executed, and if the state is false, the statements inside the else block are executed.

Syntax For If-Else C++:

if (condition){
// Executed if the condition is true
}else{
// Executed if the condition is false
}

The syntax is the same as the one given at the beginning of the article.

How Does If-Else In C++ Work?

The working mechanism of the if-else condition in C++ can be seen in the flowchart shared at the beginning of the article. In the if-else statement, we have two code blocks, either of which is implemented depending on whether the condition is true or false.

1. We begin by checking whether the condition is true or false.
2. If the condition is true, the code block following the if statement is executed. Once the execution of this block is done, the code block following else is ignored, and we move to the next line.
3. If the condition is false, the else-block code is executed, and the if block is ignored. The flow of control then moves to the line after the else code block.

If-else in C++ is also referred to as the control flow statement since it controls the flow of a program and is the most commonly used statement. Let’s take the example where we are testing the condition (a>b).

• Here if a>b holds true, then the code after the if statement is executed. The code in the else-block is ignored. After this, the program moves to the next line.
• Contrarily, if a>b is false, then the code in the if-block is ignored, and the else-block is executed. After that, the program execution moves to the next line after that.

Below is a code implementation showcasing the if-else statement in C++.

Code Example:

Output:

Student has failed

Explanation:

In the sample C++ program-

1. We first declare an integer variable marks inside the main() function and initialize it with the value of 28.
2. As mentioned in code comments, we then employ an if-else statement to check if the student has passed or failed.
3. We check the condition to see if the value of marks variable is greater than 40. If the condition marks>40 is true, then we use the cout statement to print Student has passed to the console.
4. If the condition marks<40 is false, then we use the cout statement to print Student has failed.
5. Since here, marks=28<40, the cout command after the else statement is executed, and we get the output- Student has failed.

If-Else-If Ladder Statement In C++

The if-else-if ladder is similar to the switch statement, where we get multiple options, and one among them is selected. As soon as the condition matches, the statement inside that respective block is executed, and the rest of the block is skipped. This continues until none of the statements matches, and the control is transferred to the last/ default else-block.

Syntax:

if (boolean expression 1){
// Execute this if expression1 is true
}
else if (boolean expression 2){
//Execute this if expression2 is true
}else{
//Execute this if none of the above expressions are true
}

How Does If-Else-If Ladder Statement In C++ Work?

The working of the ladder statement is depicted in the flow diagram below and explained ahead.

The if-else-if ladder in C++ is used to execute a code block/ statement conditional upon certain expressions being met. Note that only one code block gets executed according to the matching condition.

Like other flow control methods/ statements, the ladder statement begins by checking whether a condition/ expression has been met.

1. We check if the boolean expression 1 in the first if-block is true. If it is true, then the code inside the if-block is executed, and all the else-blocks are ignored.
2. If boolean expression 1 is false, the control flow goes to the else-if condition (here, boolean expression 2).
3. If expression 2 is true, then the code inside the respective else-if-block is executed, and all other else-blocks are ignored.
4. If both expressions 1 and 2 are false, the control goes to else-block 2, and the program verifies condition/ boolean expression 3. If it is true, the code inside else-block two is executed, and all other else-blocks are ignored. If it is false, the control goes to the next else condition/ expression.
5. This is continued until none of the conditions/ expressions match. The control transfers to the last else-block, and the program's normal execution continues.

To better understand the concept, look at the code example below, which implements the if-else-if ladder statement in C++.

Code Example:

Output:

Grade B

Explanation:

The C++ code above illustrates the functioning of an if-else-if ladder statement. The program takes marks of a student as input and prints the grade based on various conditions.

1. We begin by initializing an integer variable marks with the value 80 inside the main() function.
2. Then, we create an if-else-if ladder statement where the first condition/ expression checks if marks exceed 90. If the condition marks>90 is true, the cout statement in corresponding if-block prints- Grade A.
3. If marks<90 is false, the execution moves to the else-block to check expression/ condition 2, i.e., marks>80. If this condition is true, the cout statement in corresponding else-block prints- Grade B.
4. If condition marks<80 is false, then the program proceeds to check condition 3, and so on.
5. Since condition 1 is false here, but condition 2 is met, the output displayed is Grade B.

Nested If Statements In C++

Nested if statements in C++ refer to a conditional statement where one if-statement is placed inside another if-statement. This is used when we want to add one condition inside another condition. We can have any number of nested if statements in C++.

Syntax Of Nested If-Statement In C++:

if (condition1){
// Executes this if condition1 is true
if (condition2){
// Executes this if condition2 is true
}
}

We can similarly construct a nested if-else statement in C++. Its syntax is discussed below.

Syntax Of Nested If-Else In C++:

if (condition1) {
// Executes this if condition1 is true
if (condition2) {
// Executes this if condition2 is true
} else {
// Executes this if condition2 is false
}
} else {
// Executes this if condition1 is false
}

How Do Nested If Statements Work In C++?

The nested-if statement in C++ simplifies the decision-making process in complex situations where multiple conditions must be met simultaneously. Here is how these work:

• At first, the condition (i.e., condition 1) in the first if-block is checked. If condition 1 is true, the program enters the if-block.
• Inside this if block, there is another if-block, and the second condition (i.e., condition 2) is checked.
• If condition 2 is true, the code inside the nested if-block is executed.
• If both the if-conditions are false, the program flow moves outside the statement, and the next line of code is executed as normal.
• It can be concluded that for nested-if statements in C++, only a particular block is executed based on a condition.

Code Example:

Output:

n3 is the largest number

Explanation:

In the example above-

1. We declare and initialize three integer variables, n1, n2, and n3, with the values 12, 16, and 20, respectively.
2. Then, we create a nested if-else statement to find the largest number among three numbers.
3. The nested statement starts with condition 1, which is n1>n2.
4. If condition 1 is true, we move to the if statement nested inside the first if-else statement. Here, condition 2 is n1>n3, which checks if n1 is greater than n3.
5. If both if-conditions are true, then the cout statement in the second if-block is executed. It prints the string message- n1 is the largest number.
6. If condition 1 is true, but condition 2 is false, then the cout statement inside the nested else block is executed to print n3 is the largest number.
7. If condition 1 is false, we move to the corresponding else block, which contains another if-else statement.
8. Inside this, the program verifies condition 3, i.e. n2>n3. If condition 3 is true, the cout statement in the corresponding if-block is executed, and it prints- n2 as the largest number.
9. If both conditions 1 and 3 are false, we move to the else-block after condition 3. The cout statement then prints n3 is the largest number.
10. Since, in our example, none of the conditions is true, the last else-block is executed, and the corresponding message is printed.

Alternatives To Conditional If-Else In C++

While the if-statements are some of the most commonly used decision-making/ condition statements, there are some alternatives that can be used. These include the switch case and jump statements. Let's discuss these alternatives and see how they are implemented.

Switch Case Statement In C++

In C++, the switch case statement provides a convenient way to execute different blocks of code based on the value of a single expression. It is similar to the if-else-if ladder, where we have multiple choices, and a block of statements is executed based on which choice we make. It's particularly useful when dealing with multiple possible values for a variable and simplifies the code compared to using multiple nested if-else in C++.

Syntax:

switch(expression){
case 1: //statement;
break;
case 2: //statement;
break;
......
default: //statement if none of the case match;
break;
}

How Does Switch Case Work?

The switch case in C++ evaluates an expression provided within parentheses after the switch keyword.

• It compares the value of the expression sequentially with constant values specified in each case label within the switch block.
• If a match is found, the corresponding block of code following that case label is executed.
• After executing the code within a matching case block, the program encounters a break statement, which exits the switch block, skipping any subsequent case blocks.
• If none of the case values match the expression value and a default case is provided, the code within the default case block is executed.
• Once the code within a case block (or default block) is executed, the control exits the switch statement and continues with the code following the switch block.
• The default case is optional; if omitted and no case labels match the expression value, the switch statement does nothing, and control continues with the code following the switch block.

Code Example:

Output:

Option 2

Explanation:

In the above code snippet, we take an integer variable x as input whose value is 2. Using the switch case statement, the value of x is matched with the expression of the switch case. Since here, case 2 matches with the value 2, the statement Option 2 gets printed as output.

Jump Statements & If-Else In C++

Jump statements in C++ are used to change the conditional flow of a program. There are four types of jump statements in C++, namely, break, continue, goto, and return. Each of these is explained ahead.

Break Statements In C++

The break statement is used primarily inside loops (like for loop, while loop, or do-while loop) and switch statements. When encountered, it causes immediate termination of the loop or switch block in which it appears. Control then passes to the statement following the terminated loop or switch block.

Syntax:

break ;

Working Of Break Statement In C++:

The break statement is primarily used to exit from loops, switch-case and even if-else in C++. Its working mechanism is as follows:

• The break statement is placed within the body of a loop or any other control statement.
• When encountered, the break statement immediately terminates the execution of the loop or statement that encloses it.
• Control then passes to the line of code following the terminated loop or control statement, effectively ending further iterations of the loop or control statement.
• It's important to note that the break statement does not affect the conditions of the loop or control statement itself; it simply provides a means to exit prematurely based on certain conditions.

Code Example:

Output:

Number found in an array

Explanation:

In the above code snippet, we take an array as input and check if a number is present in the array or not. As soon as the number is found, we terminate the loop using the break statement.

Continue Statement In C++

The continue statement is also used within loops. When encountered, it causes the current iteration of the loop to end prematurely, and the control jumps to the next iteration, bypassing any remaining code within the loop block for the current iteration.

Syntax:

continue;

Working of Continue Statement:

• The continue statement is placed within the body of a loop, such as a for loop, while loop, or do-while loop. This can be executed with the help of if-else in C++.
• When encountered, the continue statement immediately stops the current iteration of the loop.
• Control then jumps to the next iteration of the loop, bypassing any remaining code within the loop body for the current iteration.
• The loop's condition (if it's a while or a do-while loop) or the increment portion (if it's a for loop) is then evaluated, and the loop continues with the next iteration accordingly.
• It's important to note that the continue statement does not terminate the loop itself; instead, it simply skips the remaining code for the current iteration and proceeds with the next iteration.

Code Example:

Output:

1 2 4 5

Explanation:

In the above code snippet, we run a loop from 1 to 5. As the value of i becomes 3, we continue to the next iteration without printing the value 3. After that, the normal execution of the program takes place, and we get 1 2 4 5 as output.

Goto Statement In C++

The goto statement in C++ is also known as the unconditional jump statement, which is used to jump from one part of the function to the other. A target statement is specified with the help of a user-defined label. The control always goes to the statement after the specified label.

Syntax:

label:
.....
.....
goto label;

Working of Goto Statement

• The goto statement is followed by a label identifier, which marks a specific location in the code.
• When encountered, the goto statement transfers control to the labelled statement elsewhere in the code.
• The labelled statement is typically identified by a unique label followed by a colon (:), and it can be placed anywhere within the same function or code block as the goto statement.
• Upon reaching the labelled statement, execution continues from that point onwards, irrespective of the normal control flow.

Code Example:

Output:

1 2 3 4 5

Explanation:

In the above code snippet, we make use of the goto statement to print numbers from 1-5. We take an integer variable n as 1 and print the value of n until the value is less than or equal to 5. In this case, we get 1 2 3 4 5 as output.

Return Statement In C++

The return statement is used within functions to exit the function and return a value to the caller. It can also be used to exit early from a function without returning a value in case of functions with a void return type. When encountered, it immediately terminates the function execution and returns control to the calling function along with the specified return value, if any.

Syntax:

return[expression];

Working of Return Statement:

• The return statement is followed by an optional expression, which represents the value to be returned to the caller.
• When encountered, the return statement immediately terminates the function execution and returns control to the calling function.
• If a return value is specified, it is evaluated, and control, along with the return value, is passed back to the calling function.

Code Example:

Output:

Difference is 10

Explanation:

In the above code snippet, we write two functions to find the difference between 2 numbers. The diff() function calculates the difference and returns it. The main() function uses this to find the difference, which is 10 in this case, and print it as the output.

Conclusion

The if-else statement is a fundamental tool in C++ programming for implementing decision-making logic. It allows developers to control the flow of their programs based on specific conditions. In this article, we discussed if-else in C++ and how they facilitate the decision-making process in programs. We have discussed the syntax and implementation of the various types of statements, i.e., nested if-else statements, simple if, if-else, and if-else-if ladder. We also know that there are alternatives to conditional statements, including switch and jump statements.

Understanding how to use if-else in C++ effectively is essential for writing clear, concise, and efficient code. Whether it's simple conditions or complex nested scenarios, mastering if-else statements is a key step towards becoming proficient in C++ programming.

Also read- 51 C++ Interview Questions For Freshers & Experienced (With Answers)

Frequently Asked Questions

Q. Can I use two if statements in C++?

Yes, you can use multiple if statements in C++. There is no restriction on the number of if statements you can use within a C++ program or within a function. Each if statement is evaluated independently based on its condition, and the corresponding code block is executed if the condition is true.

Here's an example of using multiple if statements in C++:

Output:

x is greater than 5
x is less than 15

Explanation:

In this example, there are two if statements, each with its own condition. Both conditions are evaluated independently, and if they are true, the corresponding message is printed to the console.

Q. What is the basic syntax of if-else C++ statements?

In C++, the if-else statement is the most used form of decision-making statement. It is used to decide which block of statement will be executed based on the conditional statement. The condition has boolean return values, i.e., true or false.

If the condition is true, the statements inside the if block are executed, and if the state is false, the statements inside the else block are executed.

Syntax:

if (condition){
// Executes this if the condition is true
statements;
}else{
// Executes this if the condition is false
statements;}

Q. Can I use multiple else if in C++?

Yes, we can do that using an if-else-if ladder. It is similar to the switch variable statement, where we get multiple options, and one among them is selected. As soon as the condition matches, the statement inside that block is executed, and the rest of the block is skipped. This continues until none of the single statements matches, and the control is transferred to the corresponding else block.

Q. What are the four types of if statements?

At times, there are situations where the program needs to make a decision, and based on that, the flow of the program is decided. In general, decision-making statements in programming help the compiler to decide the direction of the flow of program execution. The different types of if statements available in C++ are:

1. Simple if statement
2. Simple If-else statement
3. Nested if statement
4. If-else-if ladder statement

Q. How many conditions do we have in if-else statements?

In if-else statements, there is typically a single condition specified in the if-block.

1. If the statement condition is true, then the code block associated with the if statement is executed.
2. If the condition is false, the code block associated with the else statement (if present) is executed.

So, even though there is a single condition, there are two possible ways for control to flow. This way, the if-else C++ statements help in decision-making.

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