The aim is to reverse a string using pointers given a string.
Examples:
Input: Geeks
Output: skeeG
Input: GeeksForGeeks
Output: skeeGroFskeeGApproach: To use this method, you’ll need two pointers, one for the beginning of the string and the other for the end. With the help of these two pointers, the characters are then reversed one by one.
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#include <stdio.h>
#include <string.h>
// Function to reverse the string
// using pointers
void reverseString(char* str)
{
int l, i;
char *begin_ptr, *end_ptr, ch;
// Get the length of the string
l = strlen(str);
// Set the begin_ptr and end_ptr
// initially to start of string
begin_ptr = str;
end_ptr = str;
// Move the end_ptr to the last character
for (i = 0; i < l - 1; i++)
end_ptr++;
// Swap the char from start and end
// index using begin_ptr and end_ptr
for (i = 0; i < l / 2; i++) {
// swap character
ch = *end_ptr;
*end_ptr = *begin_ptr;
*begin_ptr = ch;
// update pointers positions
begin_ptr++;
end_ptr--;
}
}
// Driver code
int main()
{
// Get the string
char str[100] = "GeeksForGeeks";
printf("Enter a string: %s\n", str);
// Reverse the string
reverseString(str);
// Print the result
printf("Reverse of the string: %s\n", str);
return 0;
}Output:
Enter a string: GeeksForGeeks
Reverse of the string: skeeGroFskeeG
