Thread: Segmentation Fault

I am working on a program that takes input from the command line and then works out the math equation based on what the input was. I am using if, else if, else statments to handle the argument counts. However, if I run the program without putting input on the command line it gives me a "Segmentation Fault" error. I am wanting a custom error message that says "Input Error" which is what I am trying to use the else statement for. However, it won't display input error and only displays the segmentation fault instead.

Any suggestions are appreaciated!

Code:

/*
Jacob L. Jones
Computer Programming II
*/

#include <stdio.h>
#include <math.h>

int main(int argc, char *argv[]) {

  float num1;
  float num2;
  float ans;
  char choice;

  if (argc == 4){
      sscanf(argv[1], "%f", &num1);
      sscanf(argv[2], "%c", &choice);
      sscanf(argv[3], "%f", &num2);

      switch (choice){
      case '+':
      ans = num1 + num2;
      printf("%.2f + %.2f = %.2f\n", num1, num2, ans);
      break;

      case '-':
      ans = num1 - num2;
      printf("%.2f - %.2f = %.2f\n", num1, num2, ans);
      break;

      case 'x':
      case 'X':
      ans = num1 * num2;
      printf("%.2f x %.2f = %.2f\n", num1, num2, ans);
      break;

      case '/':
      if (num2 != 0){
      ans = num1 / num2;
      printf("%.2f / %.2f = %.2f\n", num1, num2, ans);
        }
      else{
        printf("Error! Divison by Zero!\n");
      }
      break;

      default:
      printf("%c is not a valid operator!\n", choice);
     
      break;
      }
  }
  else if (argc = 3){
      sscanf(argv[1], "%c", &choice);
      sscanf(argv[2], "%f", &num1);

switch (choice){
      case 'n':
      case 'N':
      ans = -1 * num1;
      printf("-(%.2f) = %.2f\n", num1, ans);
      break;

      case 'a':
      case 'A':
      ans = sqrt (num1 * num1);
      printf("|%.2f| = %.2f\n", num1, ans);
      break;

      case 's':
      case 'S':
      if (num1 >= 0){
      ans = sqrt(num1);
      printf("Sqrt(%.2f) = %.2f\n", num1, ans);
      }
      else {
        printf("Can't find square root of negative number\n");
      }     
      break;

      default:
      printf("%c is not a valid operator!\n", choice);

      break;
 }
  }
  else {
    printf("Input Error!!!\n");
  }
}

(argc = 3) should be (argc == 3)

Thanks! You're awesome!