char * array manipulation on recursive function

Question

I have a program that calculates the edit distance of two strings. it also outputs all the edit operations to obtain the complete transformation. i wrote a recursive function that explores the matrix filled by the edit distance calculation function and reconstructs the path

void reconstruct_path(char s1, char s2 ,int i, int j , matrix_t matrix)

 void reconstruct_path(char *s1, char *s2 int i, int j , matrix_t matrix)
 {
    if(matrix[i][j].parent == -1) return;


    if (matrix[i][j].parent == MATCH) 
    {
    reconstruct_path(s1,s2,i-1,j-1,matrix);
    match_out(s1, s2 , i, j);
    return;
    }

    if (matrix[i][j].parent == INSERT) 
    {
    reconstruct_path(s1,s2,i,j-1,matrix);
    insert_out(s2, j);
    return;
    }

    if (matrix[i][j].parent == DELETE) 
    {
    reconstruct_path(s1,s2,edit,i-1,j,matrix);
    delete_out(s1, i);
    return;
    }

}`

as you can notice there are three functions that this function calls

- void match_out(char *s1, char *s2,int i, int j)
- void insert_out(char *t, int j)
- void delete_out(char *s, int i)

void match_out(char s1, char s2,int i, int j)

void match_out(char *s1, char *s2 ,int i, int j)
{
    if (s1[i] == s2[j]) 
    {
        printf("M no edit needed \n" );
    }
    else 
    {
        printf("S subst %c with %c \n",s1[i] , s2[j]);
    }
}

void insert_out(char *t, int j)

void insert_out(char *t, int j)
{
    printf("I Insert %c\n",t[j]);
}

void delete_out(char *s, int i)

void delete_out(char *s, int i)
{
    printf("D delete %c\n",s[i]);
}

this produces an output like this

from "parent" to "cousin" :

S subst p with c
S subst a with o
S subst r with u
S subst e with s
S subst n with i
S subst t with n

i want to improve this to obtain a more precise output like this:

from "parent" to "cousin" :

S subst p with c parent -> carent
S subst a with o carent -> corent
S subst r with u corent -> couent
S subst e with s couent -> cousnt
S subst n with i cousnt -> cousit
S subst t with n cousit -> cousin

Do you ave any suggestion? (i'm noto so good with C string manipulation)

[update from comments to this answer:]

What is the data type of two strings which are recieved in s1 and s2? (asked by vj1207)

They are declared in main() like this char *str_a = " parent"; char *str_b = " cousin";

Your code does not compile. You declare match_out with 5 input arguments, but use it with 4. You declare reconstruct_path with 5 input arguments, but use it with 6. — Mikhail
– Mikhail, Commented Sep 22, 2014 at 11:01

InvisibleWolf · Accepted Answer · 2014-09-22 13:11:32Z

2

You can add few line in match_out

void match_out(char *s1, char *s2, char **edit ,int i, int j)
{
    if (s1[i] == s2[j]) 
    {
        printf("M no edit needed \n" );
    }
    else 
    {
        printf("S subst %c with %c ",s1[i] , s2[j]);
        //**from here**
        printf("%s -> ",s1);
        s1[i]=s2[j];
        printf("%s\n",s1);
        //upto here
    }
}

Update

you can declare the char array as

char str[]= {'p','a','r','e','n','t'};

if you declare it as

char * str = "parent";

then you can't modify it. And that is why you were getting the mentioned error.

edited Sep 22, 2014 at 13:11

answered Sep 22, 2014 at 11:06

InvisibleWolf

1,0271 gold badge12 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

egur Over a year ago

check that j and i are not negative. also why do you pass matrix by value? you don't seem to modify it. is it a 2D array?

fitzbutz Over a year ago

1)There are no negative values. there is only one -1 that is strategically placed on matrix[0][0] as placeholder for the root element.2)yes it is a 2D array 3) It's not by value matrix_t is defined as typedef struct m_bucket ** matrix_t;

InvisibleWolf Over a year ago

what is the data type of two strings which are recieved in s1 and s2 ?

fitzbutz Over a year ago

They are declared in main() like this char *str_a = " parent"; char *str_b = " cousin";.

InvisibleWolf Over a year ago

Then that is the problem. when you declare it as char *str_a = " parent"; then you can't modify it because it will be literal. You can not modify literal. I am updating the correct way of declaration in my answer.

|

Collectives™ on Stack Overflow

char * array manipulation on recursive function

void reconstruct_path(char s1, char s2 ,int i, int j , matrix_t matrix)

void match_out(char s1, char s2,int i, int j)

void insert_out(char *t, int j)

void delete_out(char *s, int i)

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

void reconstruct_path(char *s1, char *s2 ,int i, int j , matrix_t matrix)

void match_out(char *s1, char *s2,int i, int j)

void insert_out(char *t, int j)

void delete_out(char *s, int i)

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related

void reconstruct_path(char s1, char s2 ,int i, int j , matrix_t matrix)

void match_out(char s1, char s2,int i, int j)