path: root/src/string/strverscmp.c

#define _GNU_SOURCE #include <ctype.h> #include <string.h> int strverscmp(const char *l0, const char *r0) { const unsigned char *l = (const void *)l0; const unsigned char *r = (const void *)r0; size_t i, dp, j; int z = 1; /* Find maximal matching prefix and track its maximal digit * suffix and whether those digits are all zeros. */ for (dp=i=0; l[i]==r[i]; i++) { int c = l[i]; if (!c) return 0; if (!isdigit(c)) dp=i+1, z=1; else if (c!='0') z=0; } if (l[dp]-'1'<9U && r[dp]-'1'<9U) { /* If we're looking at non-degenerate digit sequences starting * with nonzero digits, longest digit string is greater. */ for (j=i; isdigit(l[j]); j++) if (!isdigit(r[j])) return 1; if (isdigit(r[j])) return -1; } else if (z && dp<i && (isdigit(l[i]) || isdigit(r[i]))) { /* Otherwise, if common prefix of digit sequence is * all zeros, digits order less than non-digits. */ return (unsigned char)(l[i]-'0') - (unsigned char)(r[i]-'0'); } return l[i] - r[i]; }