使用c语言实现kmp算法代码

以下是使用C语言实现KMP算法的代码：

#include <stdio.h>
#include <string.hvoid computeLPSArray(char* pat, int M, int* lps)
{
    int len = 0; // length of the previous longest prefix suffix

    lps[0] = 0; // lps[0] is always 0

    int i = 1;
    while (i < M) {
        if (pat[i] == pat[len]) {
            len++;
            lps[i] = len;
            i++;
        }
        else // (pat[i] != pat[len])
        {
            if (len != 0) {
                len = lps[len - 1];
            }
            else // if (len == 0)
            {
                lps[i] = 0;
                i++;
            }
        }
    }
}

void KMPSearch(char* pat, char* txt)
{
    int M = strlen(pat);
    int N = strlen(txt);

    int lps[M];

    computeLPSArray(pat, M, lps);

    int i = 0; // index for txt[]
    int j = 0; // index for pat[]
    while (i < N) {
        if (pat[j] == txt[i]) {
            j++;
            i++;
        }

        if (j == M) {
            printf("Found pattern at index %d\n", i - j);
            j = lps[j - 1];
        }

        // mismatch after j matches
        else if (i < N && pat[j] != txt[i]) {
            // Do not match lps[0..lps[j-1]] characters,
            // they will match anyway
            if (j != 0) {
                j = lps[j - 1];
            }
            else {
                i = i + 1;
            }
        }
    }
}

int main()
{
    char txt[] = "ABABDABACDABABCABAB";
    char pat[] = "ABABCABAB";
    KMPSearch(pat, txt);
    return 0;
}

这个示例代码中，`computeLPSArray`函数用于计算模式串的最长前缀后缀的长度，`KMPSearch`函数用于在文本串中查找模式串。