array comparison

Hi, I'm new at programming, and this is my first time doing arrays...i don't know what the problem with this code is. And where should i ask for the user input of the lines?

Write a program to see if two lines from users are equivalent. They
are considered equivalent if they use the same letters, case insensitive.
The number of times a letter appears is NOT important. So AABCC is
equivalent to cbba because they both use the letters a,b, and c. Beware,
there may be spaces in the line.


#include <stdio.h>

int main() {

int a[26], b[26], i,is_same;
char ch;
for(i=0; i<26; i++){
a[i]=0;
b[i]=0;
}

do{
printf("Input a line of letters: ");
scanf("%c", &ch);
if(ch>='a'&&ch<='z')
a[ch-'a']=1;

if(ch>='A'&&ch<='Z')
a[ch-'A']=1;
}while(ch!='\n');

do{
printf("Input a line of letters: ");
scanf("%c", &ch);
if(ch>='a'&&ch<='z')
b[ch-'a']=1;

if(ch>='A'&&ch<='z')
b[ch-'B']=1;
}while(ch!='\n');

is_same=1;
for(i=0;i<=26;i++)
if(a[i]!=b[i])
is_same=0;
if(is_same==0)
printf("Not same");
else
printf("Same");

return 0;

}

Code:

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http://cboard.cprogramming.com/forumdisplay.php?s=&forumid=4

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you put the code tag around the wrong piece of information. The comparison seems really silly since all it cares about is if the same letters appear in both arrays.

You seem to have the idea down. Just try running your code and find the problems.

Quote:

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Originally posted by battoujutsu
Hi, I'm new at programming, and this is my first time doing arrays...i don't know what the problem with this code is. And where should i ask for the user input of the lines?

---

Neither do we, unless you tell us what you see when you run the program.

Change your loops to:

Code:

---

printf("Input a line of letters: ");
do
{
    ch = getchar();
    if(ch>='a'&&ch<='z')  a[ch-'a']=1;
    if(ch>='A'&&ch<='Z')  a[ch-'A']=1;
} while(ch!='\n');

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This way the trouble with scanf() won't bite you in the you-know-where.

Code:

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int a[26], b[26], i,is_same;
....
for(i=0;i<=26;i++)

---

a & b are both 26 character arrays and the for loop goes to the 27th character -- a problem. Make the comparison simply i<26

And put the code tags around the code, not a link.

Input a line of letters: ijk
Input a line of letters: Input a line of letters: Input a line of letters: Input a line of letters: ijk
Input a line of letters: Input a line of letters: Input a line of letters: Not same

This is my output....

With that output you don't see the problem? Look at WaltP's changes and you should be dang close.

Input a line of letters: ijk
Input a line of letters: Input a line of letters: Input a line of letters: Input a line of letters: ijk
Input a line of letters: Input a line of letters: Input a line of letters: Not same

This is my output....

Quote:

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Originally posted by battoujutsu
This is my output....

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1) Post your latest code.
2) Use code tags correctly.
3) Use preview to make sure it is correct.

Quzah.

Code:

---

#include <stdio.h>

int main() {

        int  a[26], b[26], i,is_same;
        char ch;

        for(i=0; i<26; i++){
                a[i]=0;
                b[i]=0;
        }
        printf("Input a line of letters: ");
        do{
                ch =getchar();
                scanf("%c", &ch);
                if(ch>='a'&&ch<='z')
                        a[ch-'a']=1;
                if(ch>='A'&&ch<='Z')
                        a[ch-'A']=1;
                }while(ch!='\n');

        printf("Input a line of letters: ");
        do{
                ch=getchar();
                scanf("%c", &ch);
                if(ch>='a'&&ch<='z')
                        b[ch-'a']=1;

                if(ch>='A'&&ch<='z')
                        b[ch-'B']=1;
                }while(ch!='\n');

                        is_same=1;

                for(i=0;i<26;i++){
                        if(a[i]!=b[i])
                                is_same=0;
                        if(is_same==0)
                        printf("Not same\n");
                else
                        printf("Same");
}

                return 0;

}

---

//Output:
Input a line of letters: AAbc

Input a line of letters: accb

Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same
Not same

Code:

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ch =getchar(); /* read character from input */
scanf("%c", &ch); /* read character from input */

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Why the scanf? The getchar function already reads a character from input. Take a look again at WaltP's code

And another thing:

Code:

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if(ch>='A'&&ch<='z')
  b[ch-'B']=1;

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Code:

---

                for(i=0;i<26 && is_same==1;i++){
                        if(a[i]!=b[i])
                                is_same=0;
                        }

                if(is_same==0)
                        printf("Not same\n");
                else
                        printf("Same");

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To add: get rid of the scanfs and change your case and the program should work.

Also, fix your formatting. You shold be indenting blocks, not everything:

Code:

---


int main()
{
    indent code
    while()
    {
        indent code
        if ()
        {
            indent code
        }
        else
        {
            indent code
        }
        indent code
    }  // end of while
    do
    {
        indent code
    } while ();
    return 0;
}


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There is discussion about where to put the open brace '{' but the indenting should be like above.
1) Once a { is used, indent 3-4 spaces
2) as a } is used, restore previous indent
This will help you find misplaced statements (like printf()) that should be outside a loop but are actually inside.