KMP输出错误，不知道错在哪

输出有问题，不知道错在哪

#include
using namespace std;
typedef struct {
    char* ch;
    int length;
}HString;
bool InitHstring(HString& L) {
    L.ch = NULL;
    L.length = 0;
    return true;
}
bool StrAssign(HString& L, char* s) {
    if (L.ch != NULL) {
        delete L.ch;
        L.ch = NULL;
    }
    int i;
    char* c;
    for (i = 0, c = s; *c; i++, c++);
    if (!i) {
        L.length = 0;
        L.ch = NULL;
    }
    else {
        L.length = i;
        L.ch = new char[i + 1];
        if (L.ch)return false;
        for (int j = 0; j < i; j++) {
            L.ch[j] = s[j];
        }
        L.ch[i] = '\0';
    }
    return true;
}
bool StrDelete(HString& L, int pos, int len) {
    if (len < 0 || pos<0 || pos + len>L.length)
        return false;
    for (int i = pos + len; i < L.length; i++)
        L.ch[i - len] = L.ch[i];
    L.length -= len;
    L.ch[L.length] = '\0';
    return true;
}
bool Getnextval(HString L, int* nextval) {
    int i = 0, j = -1;
    nextval[0] = -1;
    while (i < L.length - 1) {
        if (j == -1 || L.ch[i] == L.ch[j]) {
            i++; j++;
            if (L.ch[i] == L.ch[j])nextval[i] = nextval[j];
            else nextval[i] = j;
        }
        else {
            j = nextval[j];
        }
    }
    return true;
}
int Index(HString L, HString T, int pos, int* next) {
    int i = pos, j = 0;
    while (j < T.length && i < L.length) {
        if (L.ch[i] == T.ch[j] || j == -1) {
            i++; j++;
        }
        else {
            j = next[j];
        }
    }
    if (j >= T.length)return i - T.length;
    else return -1;
}
bool Index_Delete(HString& L, HString T, int pos) {
    int* next = new int[T.length + 1];
    Getnextval(T, next);
    int k = Index(L, T, pos, next);
    while (k >= 0) {
        StrDelete(L, k, T.length);
        pos = k;
        k = Index(L, T, pos, next);
    }
    return true;
}
bool Display(HString L) {
    cout << L.ch << endl;
    return true;
}

int main() {
    char s[] = "abc12abcd123efdk1123";
    char h[] = "12";
    HString S, T;
    InitHstring(S);
    InitHstring(T);
    StrAssign(S, s);
    cout << "主串串值为:" << endl;
    Display(S);
    StrAssign(T, h);
    cout << "模式串串值为：" << endl;
    Display(T);
    int pos = 0;
    Index_Delete(S, T, pos);
    cout << "删除后的主串值为:" << endl;
    Display(S);
    return 0;
}

你可以对比下我博客中的KMP算法，不一样的理解方式，但是是c去写的