DIFF(3) Library Functions Manual DIFF(3) NAME diff -- generate arbitrary sequence diffs LIBRARY libdiff SYNOPSIS #include <diff.h> int diff(struct diff *p, int (*cmp)(const void *, const void *), size_t size, const void *base1, size_t nmemb1, const void *base2, size_t nmemb2); DESCRIPTION The diff() function generates the shortest edit script, longest common sub- sequence, and edit distance going from an origin array of nmemb1 objects, the initial member of which is pointed to as base1; to the target array of nmemb2 objects with initial member base2. The size of each object is spec- ified by size. Objects are compared by cmp, which requires two arguments pointing to the objects being compared. It returns zero if the objects are the same, non-zero otherwise. On success, diff() sets the edit distance in p->editdist. It allocates the p->ses array of length p->sessz and fills it with the shortest common sub- sequence. It also allocates the p->lcs array of length p->lcssz and fills it with the longest common subsequence. Both arrays must be passed to free(3) by the caller. RETURN VALUES The diff() function returns <0 on memory allocation failure, 0 if the se- quence is too complicated to generate, or >0 otherwise on success. EXAMPLES The following example takes two strings, "asdf" and "fdsa", and displays the edit script to go from the first to the second. int cmp(const void *p1, const void *p2) { return *(const char *)p1 == *(const char *)p2; } void compute(void) { size_t i; int rc; struct diff p; rc = diff(&p, cmp, 1, "asdf", 4, "fdsa", 4); if (rc < 0) err(EXIT_FAILURE, NULL); if (0 == rc) errx(EXIT_FAILURE, "cannot compute distance"); for (i = 0; i < p.sessz; i++) printf("%s%c\n", DIFF_ADD == p.ses[i].type ? "+" : DIFF_DELETE == p.ses[i].type ? "-" : " ", *(const char *)p.ses[i].e); free(p.ses); free(p.lcs); } The second example looks for difference in words. int cmp(const void *p1, const void *p2) { return 0 == strcmp (*(const char **)p1, *(const char **)p2); } void compute(void) { size_t i; int rc; struct diff p; const char *origin[] = { "hello", "there" }; const char *target[] = { "hello", "world" }; rc = diff(&p, cmp, sizeof(char *), origin, 2, target, 2); if (rc < 0) err(EXIT_FAILURE, NULL); if (0 == rc) errx(EXIT_FAILURE, "cannot compute distance"); for (i = 0; i < p.sessz; i++) printf("%s%s\n", DIFF_ADD == p.ses[i].type ? "+" : DIFF_DELETE == p.ses[i].type ? "-" : " ", *(const char **)p.ses[i].e); free(p.ses); free(p.lcs); } SEE ALSO
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | EXAMPLES | SEE ALSO
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