【剑指offer】空格替换

void replaceSpace(char str[], int Length) {

assert(str != NULL || Length > 0);

int num=0;
int length = 0;
int i = 0;
while ('\0' !=str[i])
{
++length;
if (str[i] ==' ')
{
num++;
}
i++;
}
int NewLength = 2 * num + length;
int PrevofArray = length;
while (PrevofArray>=0 && NewLength >PrevofArray)
{
if (str[PrevofArray] == ' ')
{
str[NewLength--] = '0';
str[NewLength--] = '2';
str[NewLength--] = '%';
}
else
{
str[NewLength--] = str[PrevofArray];
}
--PrevofArray;
}
}