char *replace(char *str)
{
assert(str);
char *start = str;
int space_num=0;
int len = 0;
while (*start )
{
if (*start == ' ')
space_num++;
start++;
len++;
}
char*next = str + len + space_num * 2;
while (start != str)
{
if (*start == ' ')
{
*next-- = '0';
*next-- = '2';
*next-- = '%';
start--;
}
*next = *start;
next--;
start--;
}
return next;
}
int main()
{
char msg[30] = "we are happy.";//假定空间足够
printf("old: %s\n", msg);
printf("new: %s\n", replace(msg));
system("pause");
return 0;
}
