How to check if two words are anagrams in c - c

I am trying to create a programme that is able to determine whether two inputted words are anagrams of each other.
The way in which I have been told to go by my tutor is to count how many of the first letter of one word there is, then compare to the other, then repeat for the rest of the letters. Therefore if the word gets to the end, then it considers them anagrams. However that is all he has helped me with, and I am really struggling with the problem.
The programme is required to print whether or not they are anagrams like so,
Success! "Carthorse" and "Orchestra" are anagrams!
Edit: Thanks guys for all of your responses, whilst I understand the whole idea behind them, I am finding it very difficult to put them into code, would anyone be able to simply writing the annotated code for me? It's not for a homework or anything, it's simply a personal project.

It sounds like you're new to C! Welcome :)
Tasks like that can seem complex, so the first step I'd do here is break it down into steps that you can google for how to do. So:
"count how many of the first letter of one word there is, then compare to the other, then repeat for the rest of the letter"
Read in the words/create variables of them
Create an array of length 26, to store each letter of the alphabet
Loop through the first word and for each letter, add one to the correct array index (a = 0, m = 12, etc)
e.g.
int index = string[i] - 'a'; // This will subtract the ascii value from the letter, getting a = 0 etc
letterCounts[index]++; // or letterCounts[index]--;
Loop through the second word, and for each letter, subtract one from the array index
If at the end any index is not 0, it is not an anagram.

Convert both strings to lowercase characters.
Create two arrays of 26 characters for the letters of the alphabet.
Run through each string counting the letters and incrementing the appropriate element in the alphabet arrays.
Then compare the two alphabet arrays and if they are equal for each character, your strings are anagrams.

1) Convert both strings to lowercase as necessary (use tolower from ctype.h).
2) Sort each string, e.g., by using qsort from stdlib.h:
static int cmp(const void *a, const void *b) { return *(char *)a - *(char *)b; }
qsort(str1, strlen(str1), 1, (cmp));
qsort(str2, strlen(str2), 1, (cmp));
3) Compare the sorted strings with strcmp from string.h - if equal, they are anagrams, otherwise not.

Related

How do I check if a string is a palindrome using recursion, without reversing or using a duplicate array

The conditions are:(these are part of the question, so I cannot bypass them)
I cannot reverse the array, so the strrev function, or writing a reverse function is pointless.
I cannot use another array, to copy the alphabets into it
There are whitespaces and commas, etc in the string and I have to disregard those while checking, but I am not allowed to remove those from the string
Literally the approach I had in my mind melted away after reading this,
and yes I HAVE to use recursion for this.
I just thought writing a function:
int palindrome(char arr[], int length) that returns a flag=0/1
should do the trick but I'm having trouble figuring out how to check beginning and end characters without removing the whitespace or commas.
Any ideas or hints towards a possible solution to this madness?
it should work for stuff like:
noon.
Sit on a potato pan, Otis
int palindrome(char arr[], int length);
With this signature, you can throw away characters from the beginning and end of the string, without changing the string itself:
To throw away the first character, increase the pointer:
palindrome(arr + 1, length - 1);
To throw away the last character, decrease the length:
palindrome(arr, length - 1);
Now think about a recursive definition of a palindrome; something like this:
If the first or last character is not a letter, throw it away and check whether the rest is a palindrome
If the first and last character are letters, compare them
Equal? Throw them away and check whether the substring is a palindrome
Not equal? Not a palindrome
You have to implement the logic carefully; this is only a general idea.

Having hard time understanding how to us void printSp(int) in this given task,

I only really understand how to do equation in program I need help on how to approach this task, also I not really sure whats its asking of me to do.
Suppose you are given a function with the following declaration:
void printSp(int); /* prints specified number of spaces */
Write a function named printTri that takes a single argument, a character, and returns an integer value. If the character is not a capital letter (between 'A' and 'Z'), then the function simply returns 0. Otherwise, if it is a capital letter, the function will print a triangle of characters that looks like this: A ABA ABCBA ABCDCBA
NOTE: WIth a fixed-width font, the center letter in each row would line up. Write this out for yourself on paper, to figure out how many spaces should be printed on each line before the characters start. The bottom line has zero spaces. How many spaces should the top line have? The letter passed in becomes the highest letter in the triangle. For example, to print the triangle above, the caller passes in 'D'. After printing, the function returns the total number of non-space characters printed. For example, for the example triangle above, the function must return 16. You must call the printSp function, once per line, as part of your solution. (NOTE: Call printSp for every line, even when the number of spaces to print is zero.) History:
This is what I have so far I know its not much but its all I understand how to do.
if (x >='A' && x <= 'Z') printf(" A\n ABA\n ABCBA\nABCDCBA")
else return 0;
The function printSp() prints spaces.
You currently are outputting a hard coded number of spaces instead of using printSp(). Swap printf(" ") for printSp(3)
Reading the question, they want you to output a variable number of rows based on the letter provided. So for D you print the pattern you have hard coded which contains four rows and enough letters to output the D. For E you add another row.
I generally suggest students approach problems like this by starting with hardcoding, as you have. Ensure that you incorporate the required features, like printSP(). Then make the code more generic to handle other inputs.

How do I unscramble a scrambled word?

Supposed I have an array of char {A,B,C,D,E,F} and the order number is 3
Then, the scrambled word is as follow :
The first 3rd (order number) character, C is removed and saved.
{A,B,D,E,F} , {C}
Start from the following character which is D, and the first third character would be F. So, F is removed and saved.
{A,B,D,E} , {C,F}
Start from the following character (since it reached end of array index, we go back to the beginning). So start from character A, and the first third character is D.
{A,B,E} , {C,F,D}
and so on.
The resulting will be an empty original char array, and the scrambled array
{ } , {C,F,D,B,E,A}
The above algorithm can be easily implemented. I have no problems with that. What I do have problem with is unscrambling it. I am given some unscrambled char array, and its ordering, and I have to find its original char array.
I have been trying for hours now and I can't seem to find a "formula" for it. I'm guessing I'm missing something crucial. Can anyone give me a clue or hint on how to approach this problem?
Make "map string" the same length as your original, but with all the letters in sequence, like "ABCDEFGH.."
Scramble it according to the given ordering
Now, iterate through your problem string and the map string at the same time. For each character in the problem string, the map string character will say where to put it. If you have map="SQEG..." and problem="DSEG...", then 'D' goes in the 'S' position, 'S' goes in the 'Q' position, etc.
That's it. If you prefer, or if your problem string is too long, use an array of integers instead of a string for the map.

in C: reading input string, finding it in char array

writing another program, it reads a txt file, and stores all the letter characters and spaces (as \0) in a char array, and ignores everything else. this part works.
now what i need it to do is read a user inputted string, and search for that string in the array, then print the word every time it appears. im terrible at I/O in C, how do you read a string then find it in a char array?
#include <stdio.h>
...
char str [80];
printf ("Enter your word: ");
scanf ("%s",str);
char* pch=strstr(fileData,str);
while (pch!=NULL)
{
printf ("found at %d\n",pch-fileData+1);
pch=strstr(pch+1,str);
}
read in the user inputted string as a char array as well (cause strings are basically char* anyway in C)
use a string matching algorithm like Boyer-Moore or Knutt-Morris-Pratt (more popularly known as KMP) - google for it if you like for C implementations of these - cause they're neat, tried and tested ways of searching strings for substrings and pattern matches and all.
for each of these indexOf cases, print the position where the word is found maybe? or if you prefer, the number of occurrences.
Generally, the list of C string functions, found here, say, are of the format str* or strn*, depending on requirements.
One for-loop inside another for-loop (called nested loop). Go through all the letters in your array, and for each letter go through all the letters in your input string and find out if that part of the array matches with the input string. If it does, print it.

Sort Strings by first letter [C]

I have a program which places structures in a linked list based on the 'name' they have stored in them.
To find their place in the list, i need to figure out if the name im inserting is earlier or later in the alphabet then those in the structures beside it.
The names are inside the structures, which i have access to.
I don't need a full comaparison if that is more work, even just the first letter is fine.
Thanks for the help!
It's not clear to me what your question is, but something like this would work:
if (node1->name[0] <= node2->name[0]) {
...
} else {
...
}
This will compare the first letter of the name in each of the nodes.
If you have two C strings, a and b, you can simply compare their first elements:
*a == *b
Where == can be any of the six relational operators.
Remember that with C strings, the char* points to the first character in the string.
strcmp() compares two C strings and will tell you what order they're in, or if they're the same. If you don't care about case, you can use strcasecmp(). These functions won't compare any more of the strings than necessary to determine what order to return.
strcmp man page
strcasecmp man page
You can simply iterate through the list and insert the new element in the correct place based on comparisons you do while passing each element. The simplest case sensitive version can be done just by comparing the numeric values of the letters (e.g. a[0] < b[0]), or you can convert both to a common case if you want to be case-insensitive (see ctype.h). Or you can compare the whole words with strcmp.

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