Reverse the string with a pointer

Answer 1

The following is the example code for reversing the order of a string using a pointer in C:

```c
#include
#include

void invertString(char *str) {
char *start = str;
char *end = str + strlen(str) - 1;
while (start < end) {
char temp = *start;
*start = *end;
*end = temp;
start++;
end--;
}
}

int main() {
char str[] = "Hello World";
invertString(str);
printf("%s\n", str);
return 0;
}
```

In the above code:
1. First, I defined a function `revertString`, which accepted a character pointer `string` as an argument. This pointer pointed to the string to be reversed.
2. Inside the function, two pointers,`start` and `end`, are defined.`start` points to the starting position of the string (i.e.,`str 'itself), and`end`points to the end position of the string (calculated by` str1 + strlen(str1)-1', where `strlen(str1)' is the length of the string, minus 1 is the position of the end character).
3. Then, through a `while` loop, as long as the `start` pointer is smaller than the `end` pointer, the characters pointed by `start` and `end` will be swapped. After the swap is completed, the `start` pointer will be moved backward by one position (`start++`), and the `end` pointer will be moved forward by one position (`end--`).
4. In the `main` function, you define a string `str', then call the` revertString `function to reverse the order of the string, and finally output the reversed string.
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