C - Nested Switch Statements

It is possible to have a switch as a part of the statement sequence of an outer switch. Even if the case constants of the inner and outer switch contain common values, no conflicts will arise.

Syntax

The syntax for a nested switch statement is as follows −

switch(ch1){
   case 'A': 
   printf("This A is part of outer switch" );
   switch(ch2) {
      case 'A':
         printf("This A is part of inner switch" );
         break;
      case 'B':  /* case code */
   }
   break;
   case 'B':  /* case code */
}

Example

Take a look at the following example −

#include <stdio.h>
int main (){

   /* local variable definition */
   int a = 100;
   int b = 200;
   
   switch(a){
      case 100: 
      printf("This is part of outer switch\n", a);

      switch(b){
         case 200:
         printf("This is part of inner switch\n", a);
      }
   }
   printf("Exact value of a is: %d\n", a);
   printf("Exact value of b is: %d\n", b);
   return 0;
}

Output

When the above code is compiled and executed, it produces the following output −

This is part of outer switch
This is part of inner switch
Exact value of a is : 100
Exact value of b is : 200

Nested Switch-Case Statements in C

Just like nested if–else, you can have nested switch-case constructs. You may have a different switch-case construct each inside the code block of one or more case labels of the outer switch scope.

The nesting of switch-case can be done as follows −

switch (exp1){
   case val1:
   switch (exp2){
      case val_a:
         stmts;
         break;
      case val_b:
         stmts;
         break;
   }
   case val2:
   switch (expr2){
      case val_c:
         stmts;
         break;
      case val_d:
         stmts;
         break;
   }  
}

Example

Here is a simple program to demonstrate the syntax of Nested Switch Statements in C −

#include <stdio.h>
int main(){
   int x = 1, y = 'b', z='X';

   // Outer Switch
   switch (x){
      case 1:
      printf("Case 1 \n");

      switch (y){
         case 'a':
            printf("Case a \n");
            break;
         case 'b':
            printf("Case b \n");
            break;
      }
      break;

      case 2:
      printf("Case 2 \n");
      switch (z){
         case 'X':
            printf("Case X \n");
            break;
         case 'Y':
            printf("Case Y \n");
            break;
      }
   }
   return 0;
}

Output

When you run this code, it will produce the following output −

Case 1 
Case b

Change the values of the variables (x, y, and z) and check the output again. The output depends on the values of these three variables.