Question

How to remove all duplicate characters from a string in C

Answer 1

#include <stdio.h>
#include <string.h>
    
void remove_duplicate_characters(char *s) {
  for (int i = 0; i < strlen(s); i++) {
        for (int j = i + 1; s[j] != '\0'; j++) {
            if (s[j] == s[i] && s[j] != ' ') {
                for (int k = j; s[k] != '\0'; k++) {
                    s[k] = s[k + 1];
                }
                
                j--;
            }
        }
    }
}
 
int main() {
    char s[64] = "ccc x ppppprooooogggramming x c dddd";
   
    remove_duplicate_characters(s);
       
    puts(s);
}
   
   
    
/*
run:
    
c x progamin   d
   
*/

 

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Answer 2

#include <stdio.h>
#include <string.h>
    
void remove_duplicate_characters(char *s) {
    for (int i = 0; i < strlen(s); i++) {
        for (int j = i + 1; s[j] != '\0'; j++) {
            if (s[j] == s[i] && s[j] != ' ') {
                strcpy(s + j, s + j + 1);
                j--;
            }
        }
    }
}
 
int main() {
    char s[64] = "ccc x ppppprooooogggramming x c dddd";
   
    remove_duplicate_characters(s);
       
    puts(s);
}
   
   
    
/*
run:
    
c x progamin   d
   
*/

 

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