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Program to simulate calculator using switch in C

The input is the expression of the form (a op b) where a and b are the operands and op is an operator. For example 10+20. Based on the operator, the operation is performed and the result is displayed. The complete algorithm along with the flowchart is shown below:


Step 1: [Read expression of from (a+b)]
Read: a, op, b
Step 2: [perform the required operation]

case "+" : res = a+b
case "-" : res = a-b
case "*" : res= a*b
case "/" : if (b==0)
Write : "Divide by 0"

res = a/b
[End of if]
default : Write: ' Invalid operator'
[End of switch]
Step 3: [Output the result]
Write: res
Step 4: [Finished]

The equivalent C program to perform various operations such as addition, subtraction, multiplication and division is shown below:


main( )
int a, b, res;
char op; /* can be +, - , *,, or / */
printf("Enter the expression");
scanf("%d%c%d",&a, &op, &b);
case '+' :
res = a+b;
case '-':
res= a-b;
case '*':
case '/' :
printf("Div by 0\n");
printf("Invalid operator \n");
/* end of switch statement */
printf("%d %c %d = %d\n",a,op,b,res);  /* Display the result */


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