Question

How to reverse the middle N characters of array of characters in C

Answer 1

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void reverse_middle(char *s, int pos) { 
    int len = strlen(s);
    int mid = (len - pos) / 2; 
    char *tmp = (char *)malloc((len + 1) * sizeof(char));
 
    for (int i = 0; i < mid; i++) 
        tmp[i] = s[i]; 
   
    for (int i = mid + pos - 1, j = mid; i >= mid; i--, j++) 
        tmp[j] = s[i]; 
   
    for (int i = mid + pos; i < len; i++) 
         tmp[i] = s[i];
	
	tmp[len] = '\0';
	
    strcpy(s, tmp);
	
	free(tmp);
} 

int main() {
    char s[8] = "abcdefg"; 
    int pos = 3; 
    
    reverse_middle(s, pos);
	
	puts(s);
	
	return 0;
}

  
  
/*
run:
  
abedcfg
  
*/

 

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