KMP算法基于C语言

char* GetNext(char* shortstr) {
	char* next = (char*)malloc(sizeof(char) * strlen(shortstr));
	int i = 0, j = -1;
	next[0] = -1;
	while (i < (int)strlen(shortstr) - 1) {//由于下面有i++，为了防止i的值超过开辟空间范围，故(int)strlen(shortstr) - 1
		if (j == -1 || shortstr[j] == shortstr[i]) {
			i++; j++;
			next[i] = j;
		}
		else
			j = next[j];
	}
	return next;
}
int StrMatchByKMP(char* longstr, char* shortstr) {
	char* next = GetNext(shortstr);
	int l = 0, s = 0;
	while (l < (int)strlen(longstr) && s < (int)strlen(shortstr)) {//由于strlen返回无符号数，故需要强制类型转换才能与有符号正数进行比较
		if (s == -1 || longstr[l] == shortstr[s]) {
			l++; s++;
		}
		else
			s = next[s];
	}
	free(next);
	return l - s + 1;
}

参考教学视频：KMP算法实例详解(易懂)_哔哩哔哩_bilibili