Calculator Program in C

In this topic, we will discuss how we write a calculator program in the C programming language. A Calculator is a small electronic device used to perform various arithmetic operations like addition, subtraction, multiplication, division, percentage, etc. It makes our calculations easier and faster. It is a portable device that can use anywhere to perform simple mathematical operations. We use a scientific or sophisticated calculator in some situations, where we need to solve complex calculations like trigonometry functions, exponential operators, degrees, radians, log functions, hyperbolic functions etc. Let’s discuss the various ways to create a calculator program in the C language.

Algorithm of Calculator Program

Step 1: Declare local variables n1, n2, res, opt. For example, where n1 and n2 take two numeric values, res will store results and opt variable define the operator symbols.

Step 2: Print the Choice (Addition, Subtraction, multiplication, division, etc.

Step 3: Enter the Choice

Step 4: Takes two numbers, n1 and n2

Step 5: Switch case jump to an operator selected by the user

Step 6: Store result into res variable.

Step 7: Display the operation result

Step 8: Exit from the program.

Different ways to create a Calculator Program in C

Following are the different ways to write a Calculator Program in the C language.

Calculator Program in C using the switch statement
Calculator Program in C using if else if statement
Calculator Program in C using do-while loop and switch statement
Calculator Program in C using function and switch statement

Example 1: Calculator Program in C using the switch statement

Let’s write a program to create a Calculator program using switch statement

program.c

  #include   int main()  {  // declare local variables  char opt;  int n1, n2;   float res;  printf (” Choose an operator(+, -, *, /) to perform the operation in C Calculator n “);  scanf (“%c”, &opt); // take an operator  if (opt == ‘/’ )  {  printf (” You have selected: Division”);  }  else if (opt == ‘*’)  {  printf (” You have selected: Multiplication”);   }     else if (opt == ‘-‘)  {  printf (” You have selected: Subtraction”);   }   else if (opt == ‘+’)  {  printf (” You have selected: Addition”);   }     printf (” n Enter the first number: “);  scanf(” %d”, &n1); // take fist number  printf (” Enter the second number: “);  scanf (” %d”, &n2); // take second number    switch(opt)  {  case ‘+’:  res = n1 + n2; // add two numbers  printf (” Addition of %d and %d is: %.2f”, n1, n2, res);  break;    case ‘-‘:  res = n1 – n2; // subtract two numbers  printf (” Subtraction of %d and %d is: %.2f”, n1, n2, res);  break;    case ‘*’:  res = n1 * n2; // multiply two numbers  printf (” Multiplication of %d and %d is: %.2f”, n1, n2, res);  break;    case ‘/’:  if (n2 == 0)   // if n2 == 0, take another number  {  printf (” n Divisor cannot be zero. Please enter another value “);  scanf (“%d”, &n2);  }  res = n1 / n2; // divide two numbers  printf (” Division of %d and %d is: %.2f”, n1, n2, res);  break;  default:  /* use default to print default message if any condition is not satisfied */  printf (” Something is wrong!! Please check the options “);  }  return 0;  }  

Output:

Calculator Program in C

Example 2: Calculator Program in C using if else if statement

Let’s consider an example to write a simple Calculator program in C using if else if statement.

program2.c

  #include   int main()  {  // declare local variables  char opt;  int n1, n2;   float res;  printf (” Select an operator (+, -, *, /) to perform an operation in C calculator n “);  scanf (“%c”, &opt); // take an operator  printf (” Enter the first number: “);  scanf(” %d”, &n1); // take fist number  printf (” Enter the second number: “);  scanf (” %d”, &n2); // take second number    if (opt == ‘+’)  {  res = n1 + n2; // add two numbers  printf (” Addition of %d and %d is: %f”, n1, n2, res);  }    else if (opt == ‘-‘)  {  res = n1 – n2; // subtract two numbers  printf (” Subtraction of %d and %d is: %f”, n1, n2, res);  }    else if (opt == ‘*’)  {  res = n1 * n2; // multiply two numbers  printf (” Multiplication of %d and %d is: %f”, n1, n2, res);  }    else if (opt == ‘/’)  {  if (n2 == 0)   // if n2 == 0, take another number  {  printf (” n Divisor cannot be zero. Please enter another value “);  scanf (“%d”, &n2);  }  res = n1 / n2; // divide two numbers  printf (” Division of %d and %d is: %.2f”, n1, n2, res);  }  else  {  printf(” n You have entered wrong inputs “);  }  return 0;  }  

Output:

Calculator Program in C

Example 3: Calculator Program in C using do while loop and switch statement

Let’s create a Calculator program using do while loop and switch case statement in C

program3.c

  #include   #include   #include     int main()  {  // declaration of local variable op;  int op, n1, n2;  float res;  char ch;  do  {  // displays the multiple operations of the C Calculator  printf (” Select an operation to perform the calculation in C Calculator: “);  printf (” n 1 Addition  t t 2 Subtraction n 3 Multiplication t 4 Division n 5 Square t t 6 Square Root n 7 Exit n n Please, Make a choice “);    scanf (“%d”, &op); // accepts a numeric input to choose the operation      // use switch statement to call an operation  switch (op)  {  case 1:  // Add two numbers  printf (” You chose: Addition”);  printf (“n Enter First Number: “);  scanf (” %d”, &n1);  printf (” Enter Second Number: “);  scanf (” %d”, &n2);  res = n1 + n2; // Add two numbers  printf (” Addition of two numbers is: %.2f”, res);  break; // break the function    case 2:  // Subtract two numbers  printf (” You chose: Subtraction”);  printf (“n Enter First Number: “);  scanf (” %d”, &n1);  printf (” Enter Second Number: “);  scanf (” %d”, &n2);  res = n1 – n2; // subtract two numbers  printf (” Subtraction of two numbers is: %.2f”, res);  break; // break the function    case 3:  // Multiplication of the numbers  printf (” You chose: Multiplication”);  printf (“n Enter First Number: “);  scanf (” %d”, &n1);  printf (” Enter Second Number: “);  scanf (” %d”, &n2);  res = n1 * n2; // multiply two numbers  printf (” Multiplication of two numbers is: %.2f”, res);  break; // break the function    case 4:  // Division of the numbers  printf (” You chose: Division”);  printf (“n Enter First Number: “);  scanf (” %d”, &n1);  printf (” Enter Second Number: “);  scanf (” %d”, &n2);  if (n2 == 0)  {  printf (” n Divisor cannot be zero. Please enter another value “);  scanf (“%d”, &n2);  }  res = n1 / n2; // divide two numbers  printf (” Division of two numbers is: %.2f”, res);  break; // break the function    case 5:  // getting square of a number  printf (” You chose: Square”);  printf (“n Enter First Number: “);  scanf (” %d”, &n1);    res = n1 * n1; // get square of a number  printf (” Square of %d number is: %.2f”, n1, res);  break; // break the function    case 6:  // getting the square root of the number  printf (” You chose: Square Root”);  printf (“n Enter First Number: “);  scanf (” %d”, &n1);    res = sqrt(n1); // use sqrt() function to find the Square Root   printf (” Square Root of %d numbers is: %.2f”, n1, res);  break; // break the function    case 7:  printf (” You chose: Exit”);  exit(0);   break; // break the function    default:  printf(” Something is wrong!! “);  break;   }  printf (” n n ********************************************** n “);  } while (op != 7);    return 0;        }  

Output:

Calculator Program in C

Example 4: Calculator Program in C using function and switch statement

Let’s create a Calculator program using function and switch case statement in C

program4.c

  #include   #include   #include   #include     // function declarations   int addition();  int subtract();  int multiply();  int divide();  int sq();  int sqrt1();  void exit();    int main()  {  // declaration a local variable op;  int op;  do  {  // displays the multiple operations of the C Calculator  printf (” Select an operation to perform the calculation in C Calculator: “);  printf (” n 1 Addition  t t 2 Subtraction n 3 Multiplication t 4 Division n 5 Square t t 6 Square Root n 7 Exit n n Please, Make a choice “);    scanf (“%d”, &op); // accepts a numeric input to choose the operation      // use switch statement to call an operation  switch (op)  {  case 1:  addition(); /* It call the addition() function  to add the given numbers */  break; // break the function    case 2:  subtract(); /* It call the subtract() function  to subtract the given numbers */  break; // break the function    case 3:  multiply(); /* It call the multiply() function  to multiply the given numbers */  break; // break the function    case 4:  divide(); // It call the divide() function  to divide the given numbers  break; // break the function    case 5:  sq(); // It call the sq() function  to get the square of given numbers  break; // break the function    case 6:  sqrt1(); /* It call the sqrt1() function  to get the square root of given numbers */  break; // break the function    case 7:  exit(0); // It call the exit() function  to exit from the program  break; // break the function    default:  printf(” Something is wrong!! “);  break;   }  printf (” n n ********************************************** n “);  } while (op != 7);      return 0;        }        // function definition  int addition()  {  int i, sum = 0, num, f_num; // declare a local variable  printf (” How many numbers you want to add: “);  scanf (“%d”, #);  printf (” Enter the numbers: n “);  for (i = 1; i <= num; i++)  {  scanf(” %d”, &f_num);  sum = sum + f_num;  }  printf (” Total Sum of the numbers = %d”, sum);  return 0;  }    // use subtract() function to subtract two numbers  int subtract()  {  int n1, n2, res;  printf (” The first number is: “);  scanf (”  %d”, &n1);  printf (” The second number is: “);  scanf (”  %d”, &n2);  res = n1 – n2;  printf (” The subtraction of %d – %d is: %d”, n1, n2, res);  }    // use multiply() function to multiply two numbers  int multiply()  {  int n1, n2, res;  printf (” The first number is: “);  scanf (”  %d”, &n1);  printf (” The second number is: “);  scanf (”  %d”, &n2);  res = n1 * n2;  printf (” The multiply of %d * %d is: %d”, n1, n2, res);  }    // use divide() function to divide two numbers  int divide()  {  int n1, n2, res;  printf (” The first number is: “);  scanf (”  %d”, &n1);  printf (” The second number is: “);  scanf (”  %d”, &n2);    if (n2 == 0)  {  printf (” n Divisor cannot be zero. Please enter another value “);  scanf (“%d”, &n2);  }  res = n1 / n2;  printf (” n The division of %d / %d is: %d”, n1, n2, res);  }    // use sq() function to get the square of the given number  int sq()  {  int n1, res;  printf (” Enter a number to get the Square: “);  scanf (”  %d”, &n1);    res = n1 * n1;  printf (” n The Square of %d is: %d”, n1, res);  }    // use sqrt1() function to get the square root of the given number   int sqrt1()  {  float res;  int n1;  printf (” Enter a number to get the Square Root: “);  scanf (”  %d”, &n1);    res = sqrt(n1);  printf (” n The Square Root of %d is: %f”, n1, res);  }  

Output:

Calculator Program in C

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Calculator Program in C

Calculator Program in C

Algorithm of Calculator Program

Different ways to create a Calculator Program in C

Example 1: Calculator Program in C using the switch statement

Example 2: Calculator Program in C using if else if statement

Example 3: Calculator Program in C using do while loop and switch statement

Example 4: Calculator Program in C using function and switch statement

Array of Structures in C

The exit() function in C

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