CS 202 f2017 quiz 2.  cs202xy login: _____________________________________________

1. Write C code for a program that does the following.

If there is not at least one command-line argument (argc < 2) print a usage statement.

Use atof to convert the first command-line argument to a double, and store in a double variable.

Read through the remaining command-line arguments, and use atof to convert each
to double and check if each is the same as the first one.  If not, print
the difference.

If all command-line arguments are the same as the first (after converting each with atof)
then at the end print "all the same!".

Here is a sample transcript of running it a few different times ...

./lab05_quiz2 1 1 1
  all the same!

./lab05_quiz2
Usage: n1 n2 ...

./lab05_quiz2 42
  all the same!

./lab05_quiz2 10 9 8 11 12
  argv[1]-argv[2] = 1.000000
  argv[1]-argv[3] = 2.000000
  argv[1]-argv[4] = -1.000000
  argv[1]-argv[5] = -2.000000

./lab05_quiz2 32 0x20 31.9999999999999999999 3.2e1
  all the same!




























2. Play Computer.  Keep track of the values of all the variables and what is printed on the screen.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

void fun(char *s, int n, int val) {
  printf("  %d, %d\n", n, val);
  if (n <= 0) return;

  int i;
  for(i=0; i<n; i++) {
    s[i] += val;
  }
  
  fun(s, n/2, val);
  fun(s+(n/2), n/2, val+1);
}


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

  char s[10] = "000000"; // note: strlen(s) is 8

  printf("begin: %s\n", s);

  fun(s,strlen(s), 0);
  
  printf("end:   %s\n", s);
  
  return 0;
}