String Permutations

This is a discussion on String Permutations within the C Programming forums, part of the General Programming Boards category; Hi, I was doing some practice problems and one of them is to find all the different string permutations of ...

  1. #1
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    String Permutations

    Hi, I was doing some practice problems and one of them is to find all the different string permutations of ABC.

    Here is my code which gives no errors or warnings but clearly my logic is wrong somewhere and I cannot find where.

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    void swap(char *a, char *b){
    char temp;
    
    temp = *a;
    *a = *b;
    *b = temp;
    }
    
    
    
    
    void permute( char *str, int i, int n){
    
    int j, range = n - i;
    
     if (i == n)
         printf("%s\n", str);
     else{
    
          for( j = i; j <= range; j++){
          swap(&str[i],&str[n]);
          permute(str, i, j);
          swap(&str[i],&str[n]);}
    }
    }
    
    int main(void){
    
    
    char *ptr; 
    char string[] = "ABC";
    
    ptr = string;
    
    permute(ptr,0,2);
    return 0;}

  2. #2
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    Quote Originally Posted by mrkrinkle View Post

    Code:
    void permute( char *str, int i, int n){
    
    int j, range = n - i;
    
     if (i == n)
         printf("%s\n", str);
     else{
    
          for( j = i; j <= range; j++){
          swap(&str[i],&str[n]);
          permute(str, i, j);
          swap(&str[i],&str[n]);}
    }
    }
    this might be just me, but i don't think you can call a function within its own definition?

  3. #3
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    Quote Originally Posted by synhyborex View Post
    this might be just me, but i don't think you can call a function within its own definition?
    Sure you can. It's called Recursion ...

    Cprogramming.com Tutorial: Recursion

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