Question

1. Specification Write a C program to implement a simple calculator that accepts input in the following format and displays the result of the computation:

calc [operand_1] [operator] [operand_2]

The operands operand_1 and operand_2 are non-negative integers. The operator is one of the following: addition (+), subtraction (-), multiplication (x), division (/) and modulo (%).

Note: For the multiplication operator, use letter ‘x’. If you use the asterisk ‘*’, your program will not work properly

2. Implementation

• The program to be submitted is named calc.c. Use the given template calc.c and fill in your code. Complete functions main()in file calc.c.

• Note that the command-line arguments are all strings. Therefore you need to implement a function to convert a string to an integer to obtain operand_1 and operand_2.

• Sometimes users may forget the command syntax and they may type only the command “calc”. In that case, display the following reminder message:

Usage: calc [operand_1] [operator] [operand_2]

• Other than that, assume that all inputs are valid. No error checking is required on inputs.

• You may define your own variables inside functions main(). Do not use global variables (defined outside functions main()).

• You may define and implement your own function(s) inside file calc.c if needed.

• Do not use any C library functions (e.g., atoi).

• To compile the program, use the following command: gcc –o calc calc.c

• There must be at least a white space between an operand and the operator. That is how the command-line arguments are separated.

3. Sample Inputs/Outputs

See file calc_io.txt for sample inputs and outputs

//////////Calc.c//////////////////Calc.c//////////////////Calc.c//////////////////Calc.c////////
// CALC.C
#include 
#include 


  /*****  YOU MAY ADD YOUR OWN FUNCTION(S) HERE.  *****/


/* Implement a simple calculator. 
   Input: two operands and one operator as command-line arguments.
   Output: the result displayed on the standard output. 
 */

void main( int argc, char *argv[] )
{
  int result = 0;  /* stores the result of the arithmetic operation */


  /*****************************************/
  /***** ADD YOUR CODE BELOW THIS LINE *****/



  /***** ADD YOUR CODE ABOVE THIS LINE *****/
  /*****************************************/

  /**** DO NOT ADD OR CHANGE ANYTHING BELOW THIS LINE ****/

  printf( "%d\n", result );
}

//////////////////////////SAMPLE INPUT OUTPUT ///////////////////////////////////////////////////////////////SAMPLE INPUT OUTPUT ////////////////////////////////////////////////////////

indigo 580 % calc
Usage: calc [operand_1] [operator] [operand_2]
indigo 581 % calc 12 + 10
22
indigo 582 % calc 15 - 10
5
indigo 583 % calc 20 - 55
-35
indigo 584 % calc 20 / 7
2
indigo 585 % calc 20 % 7
6
indigo 586 % calc 50 x 11
550

Answer 1

#include<stdio.h>
//defintion of function string_to_int
int string_to_int(char str[])
{
    int temp,n=0,i;
    //loop to convert the string to int
    //In this loop we read the each character and
    //subtract that character from '0' ascii value
    //example - character is '4' read from string
    // 4 ascii value is - 52
    // 0 ascii value is - 48
    //subtract 52 - 48 = 4.In this way we convert the each string into digit.
    //Then we use below logic to convert digits into number
    for(i = 0;str[i] != '\0';i++)
    {
       temp = str[i] - '0';
       n = n *10 + temp;
    }
    //return converted number
    return n;
}
//main starts here
int main(int argc,char* argv[])
{
     char op;
     int num1,num2,result = 0;
     //argc stores the number of arguments
     //argv[0] - first argument which is executable file name
     //argv[1] = num1
     //argv[2] = operator
     //argv[3] = num2
     //calling the function string_to_int
     //return value stored in num1
     //if command line arguments syntax is wrong
     //it displays the error message
     if(argc <= 3)
     {
          printf("Usage: calc [operand_1] [operator] [operand_2]");
          return 0;
     }
     num1 = string_to_int(argv[1]);
     num2 = string_to_int(argv[3]);
     op = argv[2][0];
     switch(op)
     {
        case '+':
           result = num1 + num2;
           break;
        case '-':
           result = num1 - num2;
           break;
        case 'x':
              result = num1 * num2;
              break;
        case '/':
              result = num1 / num2;
              break;
        case '%':
              result = num1 % num2;
              break;
        default :
              printf("Invalid operator");
              return 0;
      }
      printf("%d\n",result);
      return 0;
}

1 #include<stdio.h> 2 //defintion of function string_to_int 3 int string_to_int(char str[]), int temp, n=0,i; 7/loop to convert the string to int //In this loop we read the each character and //subtract that character from 'O' ascii value //example - character is '4' read from string I/ 4 ascii value is - 52 I ascii value is - 48, //subtract 52 - 48 = 4. In this way we convert the each string into digit. //Then we use below logic to convert digits into number for(i = 0;str[i] != '\0'; i++), temp = str[i] - '0'; n = n *10 + temp; //return converted number return n; 21} 22 //main starts here 23 int main(int argc, char* argv[]),

----- - -- - - --- - - -- - - - int main(int argc, char* argv[]), Y char op; int num1, num2, result = 0; //argc stores the number of arguments //argv[0] = first argument which is executable file name //argv[1] = num1 //argv[2] = operator //argv[3] = num2 //calling the function string_to_int //return value stored in num1 //if command line arguments syntax is wrong //it displays the error message if(argc <= 3) printf("Usage: calc [operand_1] [operator] [operand_2]"); return 0; num1 = string_to_int(argv [1] num2 = string_to_int(argv[3]); op = argv[2] [0]; switch(op) 45

op = argv[2] [0]; switch(op) case '+': result = num1 + num2; break; case '-': result = num1 - num2; break; case 'x': result = num1 * num2; break; case 7 ; result = num1 / num2; break; case '%': result = num1 % num2; break; default : printf("Invalid operator"); return 0; printf("%d\n", result); return 0; 67 }

| 12 + 10

11

15 - 10

20 - 55

|- 35

20/7

n

20%7

50 x 11

550