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The switch statement

Learn multi-way selection with switch, case, break and default.

The switch statement

switch picks one of several cases based on the value of an expression. Each case starts with case and ends with break. If none matches, default runs.

int day = 3;
switch (day) {
    case 1: printf("Monday\n"); break;
    case 2: printf("Tuesday\n"); break;
    case 3: printf("Wednesday\n"); break;
    default: printf("Unknown\n");
}

switch only works with integer or char values; it cannot use strings. Each case is a label; when a match is found, flow starts there.

Fall-through behavior

Without break, flow falls through to the next case. Sometimes this is wanted; usually it's a bug.

int n = 1;
switch (n) {
    case 1:
    case 2:
    case 3:
        printf("1-3 range\n");
        break;
    default:
        printf("Outside\n");
}

Here case 1, case 2 and case 3 share the same block. For n=1, n=2 and n=3 you get the same output.

Practice Print the season with switch

Write a C program. Declare int month = 4;. Use switch (month) to print the season: for case 12, case 1, case 2 print printf("Winter\n"); break;, for case 3, case 4, case 5 print printf("Spring\n"); break;, for default print printf("Other\n");. Put #include <stdio.h> at the top.

Starter code

main.c
#include <stdio.h>

int main(void) {
    // Declare month, print season with switch
    return 0;
}

Sample solution

main.c
#include <stdio.h>

int main(void) {
    int month = 4;
    switch (month) {
        case 12: case 1: case 2:
            printf("Winter\n");
            break;
        case 3: case 4: case 5:
            printf("Spring\n");
            break;
        default:
            printf("Other\n");
    }
    return 0;
}

Expected output

Spring

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Match the switch parts

Term Meaning
switch Main statement
case Case label
break Stop
default Fallback

2 What does break do in a switch?

main.c
case 1: printf("A"); break;
  • Goes to the default case
  • Starts a new case
  • Exits the switch block Correct answer
  • Nothing

Explanation: break exits the switch block.

3 Close the switch

Question 
switch (n) {
    case 1: printf("A"); break;
    default: printf("Unknown");
____;
Answer 
switch (n) {
    case 1: printf("A"); break;
    default: printf("Unknown");
};

Explanation: The switch block closes with }.

All lessons in Beginner

1 C basics

  1. What is C?
  2. Your first program
  3. Compile and run
  4. Comments
  5. printf and escapes
  6. Summary - C basics

2 Variables

  1. Declaring variables
  2. Variable assignment
  3. const
  4. Variable scope
  5. typedef
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. char
  4. sizeof
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Menu loop
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Bitwise operators
  6. Summary - Operators

6 I/O

  1. printf formatting
  2. scanf
  3. Multiple inputs
  4. getchar and putchar
  5. puts and fputs
  6. Summary - I/O

7 Conditionals

  1. The if statement
  2. else and else if
  3. The switch statement
  4. The ternary operator
  5. Nested conditionals
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. break and continue
  5. Nested loops
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding products
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Array size
  4. Multidimensional arrays
  5. Arrays and loops
  6. Summary - Arrays

11 Strings

  1. String basics
  2. String literals
  3. strlen
  4. strcpy and strcat
  5. strcmp
  6. Summary - Strings

12 Functions

  1. Defining functions
  2. Return values
  3. Parameters
  4. Function prototypes
  5. Recursion
  6. Summary - Functions

13 Pointer basics

  1. What is a pointer?
  2. The & address operator
  3. Pointer dereference
  4. NULL
  5. Pointer arithmetic
  6. Summary - Pointer basics

14 Arrays and pointers

  1. Array name as pointer
  2. Pointer to array
  3. Passing arrays to functions
  4. Pointer loop
  5. Multidim array pointer
  6. Summary - Arrays and pointers

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String functions

  1. strchr
  2. strstr
  3. strtok
  4. sprintf
  5. sscanf
  6. Summary - String functions

17 Structs

  1. Defining structs
  2. Using structs
  3. typedef struct
  4. Array of structs
  5. Nested structs
  6. Summary - Structs

18 Memory and stack

  1. Stack and heap
  2. Automatic storage
  3. malloc
  4. free
  5. calloc and realloc
  6. Summary - Memory and stack

19 Preprocessor

  1. #define
  2. #include
  3. Conditional compilation
  4. Macro functions
  5. Header files
  6. Summary - Preprocessor

20 Beginner final

  1. Project design
  2. Data model
  3. Functions
  4. Memory management
  5. Putting it together