example.cpp

int strSub(char *cadena,char *subcadena)
{
    int i=0, ii, R=0;

    while(cadena[i]!='\0'&& R==0)
    {
        if (cadena[i]==subcadena[0])
        {
            ii=0;
            int I=i;
            while(cadena[I]==subcadena[ii]&&cadena[I]!='\0')
            {
                ii++;
                I++;
            }

            if (subcadena[ii]=='\0')
            {
                R=i;
            }
        }
        i++;
    }
    R=-1;

    return R;
}