C Switch Case Statement

C Switch Case statement is a decision making statement that allows to choose the execution of one of the many case blocks based on the value of switch expression.

C Switch statement is interchangeably used for C Switch Case statement.

In this tutorial, we will learn the syntax of C switch statement, its execution flow using flow diagram, and its usage using example programs.

Syntax of C Switch Statement

The syntax of switch statement in C programming language is given below.

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switch (expression) {
    case value_1:
      // case block 1 statement(s)
      break;

    case value_2:
      // case block 2 statement(s)
      break;

    default:
      // default block statement(s)
}

where

switch is C keyword.
expression evaluates to a value.
case is C keyword.
value_1, value_2 are the constant values which the expression could evaluate to.
case block statement(s) are the set of statements that execute when corresponding value matches the expression value.
default is C keyword.
case block statement(s) are the set of statements that execute when no case value is matched.

Note: You can have as many case blocks as required.

Flow Diagram of C Switch Case Statement

The execution flow diagram of Switch-Case statement in C is given below.

The step by step process of switch case statement execution is:

Start switch case statement.
Evaluate expression’s value.
Check if expression’s value is equal to value_1. If false go to step 5.
Execute case block 1 statement(s). Go to step 8.
Check if expression’s value is equal to value_2. If false go to step 7.
Execute case block 2 statement(s). Go to step 8.
Execute default block statement(s).
End switch-case statement.

As already mentioned, you can have multiple case blocks for your switch statement. The execution flow remains similar to that of how we transitioned from case 1 to case 2.

Example for C Switch Case statement

In the following program, we use switch case statement to implement calculator. We read two numbers and a choice of operation from user. Based on the selected operation, the corresponding case block is executed.

C Program

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#include <stdio.h>

void main() {
    int a;
    printf("Enter number, a : ");
    scanf("%d", &a);

    int b;
    printf("Enter number, b : ");
    scanf("%d", &b);

    printf("\n1. Addition");
    printf("\n2. Subtraction");
    printf("\n3. Multiplication\n\n");

    int choice;
    printf("Enter choice : ");
    scanf("%d", &choice);
    
    switch (choice) {
    case 1:
        printf("%d + %d = %d", a, b, (a + b));
        break;
    case 2:
        printf("%d - %d = %d", a, b, (a - b));
        break;
    case 3:
        printf("%d * %d = %d", a, b, (a * b));
        break;
    default:
        printf("Invalid Choice.");
    }

}

Output

Conclusion

In this C Tutorial, we learned about C Switch-Case statement.

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C Switch Case