KMP implementation

#include<string.h>
#include<stdlib.h>
#include<stdio.h>
#define MAX_LEN 500
#define MAX_PAT_LEN 10

typedef struct kmp_wrapper{
    char test_string[MAX_LEN];
    char pattern[MAX_PAT_LEN];
    int h[MAX_PAT_LEN];
}KMP;

int kmp(KMP *kmp_testcase);
void pattern_perprocess(char* pattern,int* kmp_table,int len);

int kmp(KMP *kmp_testcase){
    int len_test_string = strlen(kmp_testcase->test_string);
    int len_pattern = strlen(kmp_testcase->pattern);
    int pos_test_string = 0;
    int pos_pattern = 0;
    int occ_count = 0;
    int pos = 0;
    pattern_preprocess(kmp_testcase->pattern,kmp_testcase->h,len_pattern);
    int i=0;
    while(pos_test_string<len_test_string){
        if(pos_pattern == len_pattern){
            pos_pattern = 0;
            pos_test_string++;
        }
        while( pos_pattern<len_pattern && kmp_testcase->test_string[pos_test_string]==kmp_testcase->pattern[pos_pattern]){
            pos_test_string++;
            pos_pattern++;
            //printf("pos1 = %d pos_pattern = %d\n",pos_test_string,pos_pattern);
            if(pos_pattern == len_pattern){
                pos_pattern = kmp_testcase->h[len_pattern-1];
                pos_pattern++;
                occ_count++;
            }
        }
        if(kmp_testcase->test_string[pos_test_string]!=kmp_testcase->pattern[pos_pattern]) {
            if(kmp_testcase->h[pos_pattern]!=-1){
                pos_pattern = kmp_testcase->h[pos_pattern];
            }
            else{
                pos_pattern = 0;
                pos_test_string++;
            }
        }
    }
    return occ_count;
}

void pattern_preprocess(char *test_string,int* kmp_table,int len_string){
    //set temp[0] to -1 and temp[1] to zero
    /**
     * Here the h[i] represents the size of the longest proper prexfix of W[1..i-1] which is a suffix of W[1..i-1]
     */
    kmp_table[0] = -1; /**As no string starts before this*/
    kmp_table[1] = 0; /**As no perfix exists*/
    int pos = 2;
    int prev_longest_prefix_len = 0; /**Is actually the index*/
    while(pos<len_string){
        if(test_string[pos-1]==test_string[prev_longest_prefix_len]){
            prev_longest_prefix_len++;
            kmp_table[pos] = prev_longest_prefix_len;
            pos++;
        }
        else if(prev_longest_prefix_len>0){
            prev_longest_prefix_len = kmp_table[prev_longest_prefix_len];
        }
        else{
            kmp_table[pos] = 0;
            pos++;
        }
    }
}
int main(){
    KMP *kmp_testcase = (KMP*)malloc(sizeof(KMP));
    printf("Enter the test string:\n");
    scanf("%s",kmp_testcase->test_string);
    printf("Enter the pattern string:\n");
    scanf("%s",kmp_testcase->pattern);
    printf("Number of occurences of pattern %s in %s are %d\n",kmp_testcase->pattern,kmp_testcase->test_string,kmp(kmp_testcase));
    return 0;
}