C语言字符串匹配算法有很多种，下面介绍几种常用的算法实现。
Brute-Force算法（朴素算法）int strStr(char* haystack, char* needle) { int i, j; int len1 = strlen(haystack); int len2 = strlen(needle); for (i = 0; i <= len1 - len2; i++) { for (j = 0; j < len2; j++) { if (haystack[i + j] != needle[j]) { break; } } if (j == len2) { return i; } } return -1;}void getNext(char* needle, int* next) { int i, j; int len = strlen(needle); next[0] = -1; i = 0; j = -1; while (i < len) { if (j == -1 || needle[i] == needle[j]) { i++; j++; next[i] = j; } else { j = next[j]; } }}int strStr(char* haystack, char* needle) { int i, j; int len1 = strlen(haystack); int len2 = strlen(needle); int* next = (int*)malloc(sizeof(int) * len2); getNext(needle, next); i = 0; j = 0; while (i < len1 && j < len2) { if (j == -1 || haystack[i] == needle[j]) { i++; j++; } else { j = next[j]; } } free(next); if (j == len2) { return i - j; } else { return -1; }}#define MAX_CHAR 256int max(int a, int b) { return a > b ? a : b;}void badCharHeuristic(char* needle, int* badChar) { int i; int len = strlen(needle); for (i = 0; i < MAX_CHAR; i++) { badChar[i] = -1; } for (i = 0; i < len; i++) { badChar[(int)needle[i]] = i; }}void goodSuffixHeuristic(char* needle, int* goodSuffix) { int i, j; int len = strlen(needle); int* suffix = (int*)malloc(sizeof(int) * (len + 1)); for (i = 0; i <= len; i++) { suffix[i] = -1; } for (i = len - 1; i >= 0; i--) { if (suffix[i] == -1) { suffix[i] = len - i - 1; for (j = 0; j < i; j++) { if (needle[j] == needle[len - i + j]) { suffix[j] = len - i + j; } } } } for (i = 0; i < len; i++) { goodSuffix[i] = len - suffix[i + 1]; } for (i = 0; i <= len; i++) { goodSuffix[len] = len - suffix[i + 1]; } free(suffix);}int strStr(char* haystack, char* needle) { int i = 0, j = 0; int len1 = strlen(haystack); int len2 = strlen(needle); int badChar[MAX_CHAR]; int* goodSuffix = (int*)malloc(sizeof(int) * (len2 + 1)); badCharHeuristic(needle, badChar); goodSuffixHeuristic(needle, goodSuffix); while (i <= len1 - len2) { j = len2 - 1; while (j >= 0 && needle[j] == haystack[i + j]) { j--; } if (j < 0) { free(goodSuffix); return i; } else { i += max(goodSuffix[j], j - badChar[(int)haystack[i + j]]); } } free(goodSuffix); return -1;}以上是几种常用的字符串匹配算法的C语言
