C if-else vs switch

The choice between using if-else statements and the switch statement in C depends on the specific requirements of your program and your coding preferences. Both constructs are used for making decisions and branching in your code, but they have different use cases and advantages.

Use if-else When:

1. Multiple Conditions with Different Expressions: If you have multiple conditions, each requiring different expressions or actions, if-else is more flexible. You can specify different expressions for each if and else if condition.

 if (condition1) {
     // Code for condition1
 } else if (condition2) {
     // Code for condition2
 } else {
     // Default code
 }

2. Non-Constant Conditions: if-else allows you to evaluate non-constant conditions, making it suitable when conditions are based on runtime values or user input.

 if (user_choice == 1) {
     // Code for choice 1
 } else if (user_choice == 2) {
     // Code for choice 2
 } else {
     // Default code
 }

3. Range Checking: if-else is effective for range checking or when conditions involve complex expressions.

 if (x > 10 && x < 20) {
     // Code for x in the range (10, 20)
 } else if (x >= 20 && x < 30) {
     // Code for x in the range [20, 30)
 } else {
     // Default code
 }

Use switch When:

1. Single Value Testing: switch is ideal for cases where you need to test a single value against multiple constant values.

 switch (choice) {
     case 1:
         // Code for choice 1
         break;
     case 2:
         // Code for choice 2
         break;
     default:
         // Default code
 }

2. Falling Through: switch allows for cases to “fall through” to execute the same code for multiple values without explicitly repeating it.

 switch (day) {
     case 1:
     case 2:
     case 3:
     case 4:
     case 5:
         // Code for weekdays
         break;
     case 6:
     case 7:
         // Code for weekends
         break;
     default:
         // Default code
 }

3. Enums or Integral Types: switch is often used with integral types (int, char) or enums, where the values being tested are discrete and limited.

 enum Days { MON, TUE, WED, THU, FRI, SAT, SUN };

 switch (day) {
     case MON:
     case TUE:
     case WED:
     case THU:
     case FRI:
         // Code for weekdays
         break;
     case SAT:
     case SUN:
         // Code for weekends
         break;
     default:
         // Default code
 }

In summary, both if-else and switch are essential tools in C for making decisions in your code. The choice between them depends on the specific conditions, values, and requirements of your program. Use if-else when you have complex conditions or need to handle non-constant values, and use switch when you have a single value to test against multiple constants, especially when some cases should fall through to execute the same code.