Write a C program that runs on ocelot for a mini calculator using only the comma

Question

Write a C program that runs on ocelot for a mini calculator using only the command line options. You must use getopt to parse the command line.
Usage: minicalc [-a num] [-d num] [-m num] [-s num] [-e] value
• The variable value is the starting value.
• Value should be validated to be an integer between 1 and 99. Error message and usage shown if not.
• -a adds num to value.
• -d divides value by num.
• -m multiplies value by num.
• -s subtracts num from value.
• -e squares value. (Note: no num is needed.)
• Output should have exactly 2 decimal places no matter what the starting values are.
• If –e is included, it is executed first.
• Use standard order of operations for all operations.
Code should be nicely indented and commented. Create a simple Makefile to compile your program into an executable called minicalc.The Makefile should be called Makefile with no extension. I should be able to type make at the command line to compile your program.

CAN NOT USE CONIO.H !!

Explanation / Answer

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
   extern char *optarg;
   extern int optind;
   int c, err = 0;
   int eflag=0, mflag=0, dflag = 0, aflag=0, sflag=0;
   int mnum = 0, dnum = 0, anum = 0, snum = 0;
   float value;
   static char usage[] = "usage: minicalc [-a num] [-d num] [-m num] [-s num] [e] value ";
  
   // Set the flags and num values for each case
   while ((c = getopt(argc, argv, "em:d:a:s:")) != -1)
       switch (c) {
       case 'e':
           eflag = 1;
           break;
       case 'm':
           mflag = 1;
           mnum = atoi(optarg);
           break;
       case 'd':
           dflag = 1;
           dnum = atoi(optarg);
           break;
       case 'a':
           aflag = 1;
           anum = atoi(optarg);
           break;
       case 's':
           sflag = 1;
                snum = atoi(optarg);
           break;
       case '?':
           err = 1;
           break;
       }

   // Need at least one argument (change +1 to +2 for two, etc. as needeed)
   if ((optind+1) > argc)
   {
       printf("optind = %d, argc=%d ", optind, argc);
       fprintf(stderr, "%s: missing name ", argv[0]);
       fprintf(stderr, usage, argv[0]);
       exit(1);
   }
   else if (err)
   {
       fprintf(stderr, usage, argv[0]);
       exit(1);
   }

   // Set value to the last argument from the command line  
   value = atof(argv[argc-1]);
  
   // If value is greater than 99 or less than 1 then print an error and exit the program
   if(value > 99 || value < 1)
   {
       printf("Sorry, starting value must be between 1 and 99. %s", usage);
       exit(0);
   }

  
   /* Print which flags were set and what the arguments to the options are */
   printf("eflag = %d ", eflag);
   printf("mflag = %d, %d ", mflag, mnum);
   printf("dflag = %d, %d ", dflag, dnum);
   printf("aflag = %d, %d ", aflag, anum);
   printf("sflag = %d, %d ", sflag, snum);
  
   // If statements to execute the operations we want to do (addition, multiplication, etc.)
   if(eflag == 1)
       value *= value;
   if(mflag == 1)
       value *= mnum;
   if(dflag == 1)
       value /= dnum;
   if(aflag == 1)
       value += anum;
   if(sflag == 1)
       value -= snum;

   // These are the arguments after the command line options
   if (optind < argc)
       for (; optind < argc; optind++)
           printf("Starting Value: "%s" ", argv[optind]);
   else {
       printf("no arguments left to process ");
   }
  
   // Print the result
   printf("Result : %.2f ", value);

   exit(0);

}

makefile

minicalc : getopt.o
   cc -o minicalc getopt.c

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