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

#define BUFLEN 24

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

  char   buf[BUFLEN+1];  // +1 for the '\0'
  char*  str;                      // this DOES NOT allocate space for a string

  char*  comparisonOp[] = {"<", "==", ">"};

  char** argP;
  int    size;
  char*  catResult;
  int    cmpResult;

  // copy a string
  strcpy(buf, "test string");  // bug - is destination large enough?
  printf("buf = '%s'\n", buf);

  //strcpy(str, "test string");  // bigger bug - destination is 8 bytes!
  //printf("str = '%s'\n", str);

  // Duplicate a string 
  str = strdup(buf);
  printf("dup'ed str = '%s'\n", str);

  // Compute result string length and concatenate strings
  size = 0;
  for (argP=argv; *argP; argP++) {
    size += strlen(*argP);
  }
  catResult = (char*)malloc(sizeof(char)*(size+1));
  if ( catResult == NULL ) perror("string test main()");
  
  catResult[0] = '\0';  // make buffer into a (null) string
  for (argP=argv; *argP; argP++) {
    strcat(catResult, *argP); // concatentate *argP on the end of string pointed at by catResult
  }
  printf("\nConcatenation result:\n%s\n", catResult);
  free(catResult);

  // Compare strings
  printf("\nComparisons:\n");
  for ( argP=&argv[1]; *argP; argP++ ) {
    cmpResult = strcmp(*(argP-1), *argP);
    if (cmpResult < 0) cmpResult = -1;
    if (cmpResult > 0) cmpResult = 1;
    printf("%s %s %s\n", *(argP-1), (comparisonOp+1)[cmpResult], *argP);
  }
  
  return 0;
}