generate all permutations of string

1void permute(string a, int l, int r)  
2{  
3    // Base case  
4    if (l == r)  
5        cout<<a<<endl;  
6    else
7    {  
8        // Permutations made  
9        for (int i = l; i <= r; i++)  
10        {  
11  
12            // Swapping done  
13            swap(a[l], a[i]);  
14  
15            // Recursion called  
16            permute(a, l+1, r);  
17  
18            //backtrack  
19            swap(a[l], a[i]);  
20        }  
21    }  
22}  

1void perm(char a[], int level){
2
3    static int flag[10] = {0};
4    static char res[10];
5    // If we are the last character of the input string 
6    if(a[level] == '\0'){
7        // First we assign stopping point to result
8        res[level] = '\0';
9        // Now we print everything
10        for(int i = 0; res[i] != '\0'; ++i){
11            printf("%c", res[i]);
12        }
13        printf("\n");
14        ++counter;
15    }
16    else{
17        // Scan the original string and flag to see what letters are available
18        for(int i = 0; a[i] != '\0'; ++i){
19            if(flag[i] == 0){
20                res[level] = a[i];
21                flag[i] = 1;
22                perm(a, level + 1);
23                flag[i] = 0;
24            }
25        }
26    }
27}
28
29int main(){
30    char first[] = "abc";
31    perm(first, 0);
32    return 0;
33}

1void permutation(string s)
2{
3    sort(s.begin(),s.end());
4	do{
5		cout << s << " ";
6	}
7    while(next_permutation(s.begin(),s.end()); // std::next_permutation
8    
9    cout << endl;
10}