字符串替换

#include 
using namespace std;

int index(char S[], char T[])
{
    int lenS = strlen(S), lenT = strlen(T), i = 0, j = 0;
    while (i < lenS && j < lenT)
    {
        if (T[j] == S[i]) { i ++; j ++; }
        else { i = i - j + 1; j = 0; }
    }
    if (j == lenT) return i - lenT;
    else return -1;
}
void Replace(char S[], char T[], char V[])
{
    int lenS = strlen(S), lenT = strlen(T), lenV = strlen(V);
    int i = 0, t = index(S, T);
    while (t != -1)
    {
        i = t;
        if (lenT > lenV)
        {
            for (int k = 0; k < lenV; k ++) S[i ++] = V[k];
            for (int j = t + lenT; j <= lenS; j ++) S[i ++] = S[j];
        }
        else
        {
            for (int j = lenS; j >= i + lenT; j --) S[j + lenV - lenT] = S[j];
            for (int k = 0; k < lenV; k ++) S[i ++] = V[k];
        }
        t = index(S, T);
    }
}
int main()
{
    char S[] = "xbcxbcxbc", T[] = "bc", V[] = "X";
    Replace(S, T, V);
    cout << S;
    return 0;
}