text: #include <ccan/str/str.h>
  #include <ccan/str/str.c>
  #include <stdlib.h>
  #include <stdio.h>
  #include <ccan/tap/tap.h>
  
  #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
  
  static const char *substrings[] = { "far", "bar", "baz", "b", "ba", "z", "ar",
  				    NULL };
  
  #define NUM_SUBSTRINGS (ARRAY_SIZE(substrings) - 1)
  
  static char *strdup_rev(const char *s)
  {
  	char *ret = strdup(s);
  	unsigned int i;
  
  	for (i = 0; i < strlen(s); i++)
  		ret[i] = s[strlen(s) - i - 1];
  	return ret;
  }
  
  int main(int argc, char *argv[])
  {
  	unsigned int i, j, n;
  	char *strings[NUM_SUBSTRINGS * NUM_SUBSTRINGS];
  	
  	n = 0;
  	for (i = 0; i < NUM_SUBSTRINGS; i++) {
  		for (j = 0; j < NUM_SUBSTRINGS; j++) {
  			strings[n] = malloc(strlen(substrings[i])
  					    + strlen(substrings[j]) + 1);
  			sprintf(strings[n++], "%s%s",
  				substrings[i], substrings[j]);
  		}
  	}
  
  	plan_tests(n * n * 5 + 16);
  	for (i = 0; i < n; i++) {
  		for (j = 0; j < n; j++) {
  			unsigned int k, identical = 0;
  			char *reva, *revb;
  
  			/* Find first difference. */
  			for (k = 0; strings[i][k]==strings[j][k]; k++) {
  				if (k == strlen(strings[i])) {
  					identical = 1;
  					break;
  				}
  			}
  
  			if (identical) 
  				ok1(streq(strings[i], strings[j]));
  			else
  				ok1(!streq(strings[i], strings[j]));
  
  			/* Postfix test should be equivalent to prefix
  			 * test on reversed string. */
  			reva = strdup_rev(strings[i]);
  			revb = strdup_rev(strings[j]);
  
  			if (!strings[i][k]) {
  				ok1(strstarts(strings[j], strings[i]));
  				ok1(strends(revb, reva));
  			} else {
  				ok1(!strstarts(strings[j], strings[i]));
  				ok1(!strends(revb, reva));
  			}
  			if (!strings[j][k]) {
  				ok1(strstarts(strings[i], strings[j]));
  				ok1(strends(reva, revb));
  			} else {
  				ok1(!strstarts(strings[i], strings[j]));
  				ok1(!strends(reva, revb));
  			}
  			free(reva);
  			free(revb);
  		}
  	}
  
  	for (i = 0; i < n; i++)
  		free(strings[i]);
  
  	ok1(streq(stringify(NUM_SUBSTRINGS),
  		  "((sizeof(substrings) / sizeof(substrings[0])) - 1)"));
  	ok1(streq(stringify(ARRAY_SIZE(substrings)),
  		  "(sizeof(substrings) / sizeof(substrings[0]))"));
  	ok1(streq(stringify(i == 0), "i == 0"));
  
  	ok1(strcount("aaaaaa", "b") == 0);
  	ok1(strcount("aaaaaa", "a") == 6);
  	ok1(strcount("aaaaaa", "aa") == 3);
  	ok1(strcount("aaaaaa", "aaa") == 2);
  	ok1(strcount("aaaaaa", "aaaa") == 1);
  	ok1(strcount("aaaaaa", "aaaaa") == 1);
  	ok1(strcount("aaaaaa", "aaaaaa") == 1);
  	ok1(strcount("aaa aaa", "b") == 0);
  	ok1(strcount("aaa aaa", "a") == 6);
  	ok1(strcount("aaa aaa", "aa") == 2);
  	ok1(strcount("aaa aaa", "aaa") == 2);
  	ok1(strcount("aaa aaa", "aaaa") == 0);
  	ok1(strcount("aaa aaa", "aaaaa") == 0);
  
  	return exit_status();
  }				
  