If-Else and Switch in C – Differences, Syntax, and Examples

The main difference between If-Else and Switch in C is how they handle decision-making. The If-Else statement checks conditions that return true or false, allowing flexible comparisons using logical or relational operators. In contrast, the Switch statement checks a single expression against fixed constant values. It works well when dealing with multiple specific cases, making the code easier to manage and read.

If you want to get hands-on experience, explore Online Software Engineering Courses from top universities!

In this article, we will explore what If-Else and Switch in C are, how they work, and when to use them. You will learn their syntax, see simple examples with outputs, and understand each part of the code. A detailed table and a real-world example will highlight their differences.

Quick Tabular Comparison Between If-Else and Switch in C

The table below highlights the key differences between If-Else and Switch in C. It gives a quick overview based on condition types, flexibility, readability, and more.

What is If-Else in C?

In C programming, the If-Else statement is a conditional control structure. It helps the program make decisions based on whether a condition is true or false. If the condition is true, one block of code runs. If the condition is false, another block runs instead.

This allows programs to perform logical checks and control the flow of execution. If-Else in C is useful when the condition involves logical, relational, or mathematical expressions. You can also use nested If-Else statements to check multiple conditions in sequence.

To gain in-depth knowledge, explore the Mastering the if-else Statement in C : A Deep Dive for Intermediate Developers article!

Syntax of If-Else in C

The If-Else statement in C follows a simple and structured format. It is used to check conditions and decide which block of code should run. The syntax is easy to understand and forms the base of many decision-making programs.

Here’s the syntax:

if (condition) {
    // Code to run if the condition is true
} else {
    // Code to run if the condition is false
}

Components of the Syntax:

Let’s break down the key parts of the If-Else syntax in C:

1. if keyword
2. • It begins the condition check.
   • The program checks the expression inside the parentheses right after if.
2. condition
3. • This is a logical or relational expression.
   • If it evaluates to true (non-zero), the if block runs.
3. if block
4. • This block runs only if the condition is true.
   • It is enclosed in curly braces {}.
4. else keyword
5. • It is optional but often used.
   • It defines what should happen if the if condition is false.
5. else block
6. • This block runs only when the condition is false.
   • Like the if block, it also uses curly braces.

Example of If-Else in C

#include <stdio.h>

int main() {
    int number;

    // Asking the user to input a number
    printf("Enter a number: ");
    scanf("%d", &number);

    // Using if-else to check whether the number is even or odd
    if (number % 2 == 0) {
        // Executes if the number is divisible by 2
        printf("The number is even.\n");
    } else {
        // Executes if the number is not divisible by 2
        printf("The number is odd.\n");
    }

    return 0;
}

Output:

Enter a number: 7

The number is odd.

Explanation:

• The program asks the user to input a number.
• The if condition checks if the number is divisible by 2.
• If the result is true, it prints "The number is even."
• If the result is false, the else block prints "The number is odd."

This shows how If-Else in C lets us run code based on conditions.

When to Use If-Else?

Use the If-Else statement in C when:

• You need to check logical or relational conditions (e.g., a > b, x == y, etc.).
• The program must choose between two or more paths based on expressions.
• You want to perform range-based comparisons (like checking if a number lies between two values).
• The condition involves boolean logic (AND, OR, NOT).
• You are working with dynamic values (variables, user inputs, calculations).
• You need to nest multiple decisions using else if blocks.
• The conditions are not fixed constants, unlike what the switch statement requires.
• Your logic needs more than equality checks for decision-making.

What is Switch in C?

The Switch statement in C is a multi-way branching control structure. It allows the program to select one block of code from multiple options. It checks a variable or expression against a list of constant values. When a match is found, the corresponding block is executed.

Switch in C is ideal when you have to handle many fixed conditions, like menu selections or key-based operations. It improves readability and keeps the code clean compared to using many if-else blocks.

To gain in-depth knowledge, explore the Switch Case in C: In-Depth Code Explanation article!

Syntax of Switch in C 

The Switch statement in C allows for easy multi-way branching. It compares a variable or expression to different constant values and runs the corresponding block of code. Here's the syntax and breakdown of its components.

Here’s the syntax:

switch (expression) {
    case constant1:
        // Code to execute if expression matches constant1
        break;
    case constant2:
        // Code to execute if expression matches constant2
        break;
    // More cases as needed
    default:
        // Code to execute if no case matches
}

Components of the Syntax:

Let’s explore the important components of the Switch statement in C:

1. switch keyword
2. • The switch keyword begins the decision structure. It tests an expression against a set of possible values (the cases).
2. expression
3. • This is the value or variable that the program compares against each case.
   • The expression is evaluated once, and the result is matched with a constant value.
3. case constant
4. • Each case defines a specific constant value to compare with the expression.
   • If the value matches, the corresponding block of code runs.
4. break statement
5. • The break statement exits the switch block after a match is found.
   • Without break, the program will continue executing the subsequent cases (called “fall-through”).
5. default block
6. • The default block runs when no case matches the expression.
   • It’s optional, but it’s helpful for handling unexpected values.

Must Explore: Switch Case in C++: Syntax, Usage, and Best Practices

Example of Switch in C

#include <stdio.h>

int main() {
    int day = 3;

    // Switch statement to print the day of the week
    switch (day) {
        case 1:
            printf("Monday\n");
            break; // Exits switch after matching case
        case 2:
            printf("Tuesday\n");
            break;
        case 3:
            printf("Wednesday\n");
            break;
        case 4:
            printf("Thursday\n");
            break;
        case 5:
            printf("Friday\n");
            break;
        case 6:
            printf("Saturday\n");
            break;
        case 7:
            printf("Sunday\n");
            break;
        default:
            // Runs if no case matches
            printf("Invalid day\n");
    }

    return 0;
}

Output:

Wednesday

Explanation:

• The variable day is set to 3.
• The switch checks the value of day against each case.
• It finds that day == 3, so it executes the code in case 3.
• "Wednesday" is printed to the screen.
• The break statement exits the switch block after a match.
• If there’s no match, the default block runs instead.

When to Use Switch?

Use the Switch statement in C when:

• You have a fixed set of known values to compare against a single expression.
• The conditions involve multiple constant values (e.g., menu options, key presses).
• You want cleaner code instead of multiple if-else statements.
• You need to handle discrete values (like days of the week, grades, etc.).
• The expression is a simple variable or constant (e.g., integer, character).
• You want to use fall-through behavior (executing multiple cases under certain conditions).
• The conditions are not based on ranges (like a > b). If ranges are needed, prefer if-else.

Key Differences Between If-Else and Switch in C

Here are the key differences between if-else and switch in C:

• If-Else is flexible and can evaluate complex conditions (like a > b or x == y). In contrast, Switch works best with constant values (like integers or characters).
• If-Else can handle range-based checks (e.g., x > 10 && x < 20). On the other hand, Switch only compares a single expression with fixed values and cannot handle ranges.
• Switch supports fall-through, allowing multiple cases to share the same code block. But If-Else does not have fall-through and evaluates conditions sequentially.
• If-Else can become cluttered and harder to manage with many conditions. Meanwhile, Switch improves readability when handling many conditions based on the same expression.
• Switch tends to be more efficient when comparing a single value to many options. In contrast, If-Else may be slower when checking multiple conditions.
• Both Switch and If-Else provide a way to handle cases when no condition matches. However, Switch explicitly uses the default keyword, whereas If-Else simply continues to the next else block.

Example to Understand the Difference Between If-Else and Switch in C

Below is a code example that demonstrates how both If-Else and Switch in C can be used to check a grade and print the corresponding result. This example will help highlight the differences between the two.

Here’s the code:

#include <stdio.h>

int main() {
    int grade = 85;  // Variable holding the grade

    // Using If-Else
    printf("Using If-Else:\n");
    if (grade >= 90) {
        printf("Grade: A\n");
    } else if (grade >= 80) {
        printf("Grade: B\n");
    } else if (grade >= 70) {
        printf("Grade: C\n");
    } else if (grade >= 60) {
        printf("Grade: D\n");
    } else {
        printf("Grade: F\n");
    }

    // Using Switch
    printf("\nUsing Switch:\n");
    switch (grade / 10) {  // Dividing grade by 10 (e.g., 85 becomes 8)
        case 10:
        case 9:
            printf("Grade: A\n");
            break;
        case 8:
            printf("Grade: B\n");
            break;
        case 7:
            printf("Grade: C\n");
            break;
        case 6:
            printf("Grade: D\n");
            break;
        default:
            printf("Grade: F\n");
    }

    return 0;
}

Output:

Using If-Else:

Grade: B

Using Switch:

Grade: B

Explanation:

• If-Else:
• • We check the value of grade step by step using if, else if, and else.
  • It compares the grade with different ranges (e.g., grade >= 90).
  • If the condition matches, it prints the corresponding grade.
  • This approach is flexible, as it can handle complex conditions like ranges (>=).
• Switch:
• • We first divide grade by 10 to simplify the comparison (e.g., 85 / 10 = 8).
  • The switch statement compares the result with constant values (9, 8, etc.).
  • The case that matches the divided value (8) is executed.
  • The break statement ensures that only the matching case runs and prevents further checks.
  • Switch is more efficient when comparing a single variable to multiple fixed values.

Conclusion

In summary, If-Else and Switch are both essential decision-making structures in C. If-Else is more flexible and ideal for complex conditions, while Switch is efficient for comparing a single expression with multiple constant values. Understanding when to use each can improve the readability and performance of your code.

FAQs

1. What is the difference between If-Else and Switch in C?

The If-Else and Switch in C are both control structures used for decision-making. If-Else evaluates conditions sequentially and works well with complex conditions, whereas Switch compares a single expression to constant values, making it more efficient for handling multiple cases.

2. When should I use If-Else instead of Switch in C?

You should use If-Else in C when the conditions involve ranges (e.g., a > b or x <= y), or when comparing values that are not constants. Switch is ideal for handling a fixed set of constant values.

3. Can I use If-Else for multiple conditions?

Yes, If-Else is great for checking multiple conditions. You can use it to evaluate conditions such as ranges or boolean expressions. Switch is more suited for discrete, constant values, whereas If-Else handles more complex logic.

4. What is the fall-through behavior in Switch in C?

Fall-through in Switch in C occurs when multiple case labels share the same code block. This happens when there is no break statement. While this can be useful, it can also lead to bugs if not used carefully.

5. Can a Switch statement handle boolean expressions?

No, Switch cannot handle boolean expressions directly. It only compares an expression to constant values. For boolean conditions, If-Else is more appropriate as it can handle logical operators like && and ||.

6. How does performance compare between If-Else and Switch in C?

Generally, Switch in C is more efficient when comparing a single value to multiple options. In contrast, If-Else can be slower when checking multiple conditions, especially if the conditions are complex or have a large number of cases.

7. Does Switch handle ranges of values?

No, Switch in C can only compare a single value to constant values (like integers or characters). For ranges, you should use If-Else statements as they allow for greater flexibility in defining conditions.

8. Is there a limit to the number of cases in Switch in C?

No, there is no fixed limit for the number of cases in Switch in C. However, having too many cases can make the code difficult to manage. If you find yourself with a large number of cases, consider using arrays or functions.

9. Can Switch be used with strings in C?

No, Switch in C does not support strings directly. It can only work with integral types like integers and characters. To compare strings, you would need to use If-Else or implement string comparison manually.

10. What happens if none of the cases match in Switch?

If no case in Switch in C matches the expression, the default case (if present) will be executed. If there is no default case, the program simply skips the entire switch block.

11. Can I use If-Else and Switch together in a program?

Yes, you can use both If-Else and Switch in C in the same program. They are not mutually exclusive and can complement each other depending on the complexity and type of conditions you are evaluating.

Take a Free C Programming Quiz

Answer quick questions and assess your C programming knowledge

Start Quiz