Reverse a string (the library function cannot be used with a recursive implementation)

Reverse the two strings to set two pointers, one to the beginning of the string, and one to the address of the element at the end of the string (the address of the element in front of the "Start<end") end, as long as the two addresses point to the element to exchange.

The implementation code is as follows:

#include <stdio.h>
#include <string.h>
void reverse (char *str)
{
char tmp = 0;
Char *start;
Char *end;
start = str;
end = str + strlen (str)-1;
while (Start < end)
{
TMP = *start;
*start = *end;
*end = tmp;
Start + +;
End--;

}
}
int main ()
{
Char str[] = "abcdef";
Reverse (str);

printf ("%s", str);
return 0;
}
It can also be implemented using recursive methods:

First the first element of the string "ABCdef" is saved, and then the last element is placed in the position of the first element, the last element is assigned a value of "\", when the function is called the first address of the string is passed back to the address of an element, to determine whether its length is greater than 1, If greater than one is repeated above, the function returns the last function returned after the function has been recursively completed, assigning the value of the last function saved to the position of the len-1 in the function.

The code is implemented as follows:

#include <stdio.h>
#include <assert.h>
int Str_len (char *str)//Simulation implementation strlen function
{
ASSERT (str);
int count = 0;
while (*STR)
{
count++;
str++;
}

return count;
}
void reverse (char *str)//String reverse function
{
char *p = str;
char tmp = 0;
int len = 0;
len = Str_len (p);
if (Len > 1)
{
TMP = p[0];
P[0] = p[len-1];
P[len-1] = ' + ';
Reverse (p + 1);
P[LEN-1] = tmp;
}
}
int main ()
{
Char str[] = "abcdef";
Reverse (str);
printf ("%s\n", str);
System ("pause");
return 0;
}

Reverse a string (the library function cannot be used with a recursive implementation)