Examples of switch statements

The following switch statement contains several case clauses and one default clause. Each clause contains a function call and a break statement. The break statements prevent control from passing down through each statement in the switch body.

If the switch expression evaluated to '/', the switch statement would call the function divide. Control would then pass to the statement following the switch body.

char key;

printf("Enter an arithmetic operator\n");
scanf("%c",&key);

switch (key)
{
   case '+':
      add();
      break;

   case '-':
      subtract();
      break;

   case '*':
      multiply();
      break;

   case '/':
      divide();
      break;

   default:
      printf("invalid key\n");
      break;
}

If the switch expression matches a case expression, the statements following the case expression are processed until a break statement is encountered or the end of the switch body is reached. In the following example, break statements are not present. If the value of text[i] is equal to 'A', all three counters are incremented. If the value of text[i] is equal to 'a', lettera and total are increased. Only total is increased if text[i] is not equal to 'A' or 'a'.

char text[100];
int capa, lettera, total;

// ...

for (i=0; i<sizeof(text); i++) {

    switch (text[i])
    {
       case 'A':
         capa++;
       case 'a':
         lettera++;
       default:
         total++;
    }
}

The following switch statement performs the same statements for more than one case label:

/**
 ** This example contains a switch statement that performs
 ** the same statement for more than one case label.
 **/

#include <stdio.h>

int main(void)
{
  int month;

  /* Read in a month value */
  printf("Enter month: ");
  scanf("%d", &month);

  /* Tell what season it falls into */
  switch (month)
  {
     case 12:
     case 1:
     case 2:
        printf("month %d is a winter month\n", month);
        break;

     case 3:
     case 4:
     case 5:
        printf("month %d is a spring month\n", month);
        break;

     case 6:
     case 7:
     case 8:
        printf("month %d is a summer month\n", month);
        break;

     case 9:
     case 10:
     case 11:
        printf("month %d is a fall month\n", month);
        break;

     case 66:
     case 99:
     default:
        printf("month %d is not a valid month\n", month);
  }

  return(0);
}

If the expression month has the value 3, control passes to the statement:

printf("month %d is a spring month\n",
month);

The break statement passes control to the statement following the switch body.