I am probably not going to get help here because my question is far from being specific (I don't even know what exactly wrong with it) but, according to my professor's tests, there is something wrong with it (wrong in terms of correctness - it doesn't provide correct number of direct and indirect matches) (I have no access to his tests). As far as I have been testing, it passes all of my tests. However, there are over a couple hundred million possible outcomes (I think) and I can't test them all because I don't know how to do automated testing...
Here is my code that performs the "logic" part of the game called mastermind, which is compares a string of randomly generated letter (8 max) with user input string (a guess). I wanted to see if anyone has encountered this game in the past and knows the logic of how it supposed to compare two strings and generate the correct number of exact and inexact guesses.
// userInput->position - a length of a string(max 8)
// userInput->code - randomly generated code
// userInput->arr - user input string
void checkForExactMatch(Data* userInput) {
int i;
for (i = 0; i < userInput->position; i++) {
if (userInput->code[i] == userInput->arr[i]) {
userInput->exactMatch++;
userInput->arr[i] = 'a';
}
else
checkForInExactMatch(userInput, i);
}
}
void checkForInExactMatch(Data* userInput, int i) {
int j;
for (j = 0; j < userInput->position; j++) {
if (userInput->arr[j] == userInput->code[i]) {
userInput->arr[j] = 'a';
userInput->inExactMatch++;
break;
}
}
}
Looking over your code there were a couple of observations to be made. First in your for checkForExactMatch() the call to checkForInExactMatch is inside your for loop. So on the first mismatch you call checkForInExactMatch and when you return from checkForInExactMatch -- you call it again on the next iteration unless your first mismatch just happens to be on the final character.
To address that issue, you should fully determine whether you have an exact match or not, completing the for loop before checkForInExactMatch is called.
In your checkForInExactMatch, you have to decide whether a single common-character or some minimum length substring constitutes an inexact match.
It sounds like you have things worked out, and good job for pushing through to a solution. Depending on how you approached it, keeping a simple flag in checkForExactMatch()such as int matched = 1; and then loop turning your test around
for (i = 0; i < userInput->position; i++)
if (userInput->code[i] != userInput->arr[i]) {
matched = 0;
break;
}
Then it's just a simple test of
if (matched) {
userInput->exactMatch++;
userInput->arr[i] = 'a';
}
else
checkForInExactMatch(userInput, i);
So long as what you have done accomplishes something similar, you are fine. Let me know if you have further questions.
Related
Just wondering if these variations of for loops are more efficient and practical.
By messing with the c for loop syntax i can embedd statements that would go in the loop-body into the loop-head like so:
Example 1:
#include <stdio.h>
int main(int argc, char ** argv)
{
// Simple program that prints out the command line arguments passed in
if (argc > 1)
{
for(int i = 1; puts(argv[i++]), i < argc;);
// This does the same as this:
// for(int i = 1; i < argc; i++)
// {
// puts(argv[i]);
// }
}
return 0;
}
I understand how the commas work in the for loop it goes through each statement in order, evaluates them then disregards all but the last one which is why it is able to iterate using the "i < argc"condition. There is no need for the final segment to increment the i variable as i did that in the middle segment of the loop head (in the puts(argv[i++]) bit).
Is this more efficient or is just just cleaner to seperate it into the loop body rather than combine it all into one line?
Example 2:
int stringLength(const char * string)
{
// Function that counts characters up until null terminator character and returns the total
int counter = 0;
for(counter; string[counter] != '\0'; counter++);
return counter;
// Same as:
//int counter = 0;
// for(int i = 0; string[i] != '\0'; i++)
//{
// counter++;
//}
//return counter;
}
This one seems more efficient than the version with the loop body as no local variable for the for-loop is initialised. Is it conventional to do these sorts of loops with no bodies?
Step 1: Correctness
Make sure code is correct.
Consider OP's code below. Does it attempt to print argv[argc] which would be bad?
if (argc > 1) {
for(int i = 1; puts(argv[i++]), i < argc;);
I initially thought it did. So did another user. Yet it OK.
… and this is exactly why code is weak.
Code not only should be correct, better code looks correct too. Using an anti-pattern as suggested by OP is rarely1 as good thing.
Step 2: Since code variations have the same big O, focus on understandably.
Sculpt your code – remove what is not needed.
for (int i = 1; i < argc; i++) {
puts(argv[i]);
}
What OP is doing is a trivial optimization concern.
Is premature optimization really the root of all evil?
Is it conventional to do these sorts of loops with no bodies?
Not really.
The key to the style of coding is to follow your group's style guide. Great software is often a team effort. If your group's likes to minimize bodies, go ahead. I have seen the opposite more common, explicit { some_code } bodies.
Note: int stringLength(const char * string) fails for strings longer than INT_MAX. Better to use size_t as the return type – thus an example of step 1 faltering.
1 All coding style rules, except this rule, have exceptions.
I am making a little game using getch and print, as a bit of a test for myself, and surprisingly it actually works quite well but i'm having a bit of an issue. I am printing all of the tiles using a loop and printf, and of course as the loop has to process a bit, everytime the character moves, it re-prints everything, which causes a bit of a stutter, due to the loop printing. What can I possibly do to combat this?
This is how the tiles are printed
void Game() {
int X = 0;
int Y = 0;
int PrintWall = 0;
do {
for (int i = 0; i < 80; i++) {
X = i;
PrintWall = 0;
for (int j = 0; j < 12; j++) {
if (X == WallX[j]) {
if (Y == WallY[j]) {
PrintWall = 1;
}
}
}
if (X == Player.XCoor && Y == NegativeToPositive(Player.YCoor)) {
printf("#");
}
else if (PrintWall == 1){
printf("#");
}
else {
printf(".");
}
}
Y++;
} while (Y != 22);
}
You may want to try building the full screen of data into a buffer first and THEN print it. Start with an array of characters as long as you need it to be:
char buffer[SIZE_X * SIZE_Y];
Then go through your loop above, but instead of using printf(), set the character at that location in the buffer to what you want it to be:
buffer[(SIZE_X * Y) + X] = /* '#', '#', or '.' as appropriate */
Then, once you are through the loop, you will print the whole buffer to the screen:
printf(buffer);
Just make sure you don't accidentally overwrite your null terminator with another character or you may get more text than you bargained for.
That is just a limitation of printing the whole "board" on every change. The only way to fix it is to only print what changes. Depending on your OS etc you may be able to print individual characters or lines instead of the whole board.
You could look at a library like curses to give character level control (there may be something better - don't know, I don't do this often enough to know ;-)
As other answers have said, printing in bigger pieces (like a whole buffer at a time) is better than printf for each individual character but you will still probably have the same issue but it is certainly worth a try.
Consider separating initialization and the game loop. Draw the game board as init and update everything in your do-while-loop.
You should limit the number of moving walls.
If a wall moves, you delete/replace the wall mark # at the old position, write out the mark on your interface at the new place and then change the mark's data in the arrays.
After that, you just check, if the new player position hits an obstacle. If no, delete/replace the current mark of the player with the default character and write the new position.
If the two players hit each other, you would need your old condition.
I want to initialize an 16-cel-long array with 0, 1, 2 and 3 by blocks of four cels. So here is my first attempt at this:
int main(void) {
int t[16];
int i;
for (i = 0; i<=15; t[i++]=i/4)
{
printf("%d \n", t[i]);
}
return 0;
}
However, here is what I get. I know I can do it differently by just getting the affectation into the for loop, but why does this not work?
EDIT: Please do note that the printf only serves to check what the loop did put in the array.
The initialization works fine; you're just printing the cell before initializing it. Remember that the loop increment is done after each iteration. If you unroll the loop, you have:
i = 0; /* i is now 0 */
print(t[i]); /* prints t[0] */
t[i++] = i/4; /* sets t[0] */
/* i is now 1 */
print(t[i]); /* prints t[1] */
t[i++] = i/4; /* sets t[1] */
/* i is now 2 */
print(t[i]); /* prints t[1] */
/* etc. */
As well as the off-by-one errors with the loop begin/end that have been mentioned in other posts, this code:
t[i++]=i/4
causes undefined behaviour because i is read and written without a sequence point. "Undefined behaviour" means anything can happen: the value could be 3, or 4, or anything else, or the program could crash, etc.
See this thread for more in-depth discussion, and welcome to C..:)
I do not understand what you are trying to accomplish, but please let me show you a similar piece of code, first.
int main(void) {
int t[16];
int i;
//edited the code; providing standard way to do the task
for (i = 0; i<=15; i++)
{
t[i]=i/4;
printf("%d \n", t[i]);
}
return 0;
}
EDIT:
The while loop should be written that way:
int i = 0;
while (i<=15){
t[i] = i%4;
i++;
}
Which means set t[i] equal to i%4 and then increment i.
Since you are a beginner, I've updated the for loop and it now provides a standard way to do your task. It's better to have a simple increment on the third for loop command; do the rest of the job inside the for loop, as described above.
#naltipar: Yeah, I just forgot to initialize the first cel, just like grawity pointed out. Actually, the version I wrote for myself was with i++ but even then, since the third expression is executed after each loop, it sent out the same result. But whatever, it is fixed now.
However, I've got another problem which I'm sure I'm missing on but still can't figure it out:
int i = 0;
while (i<=15)
t[++i] = i%4;
This was first:
for(i = 0; i<=15; t[++i] = i%4);
but it resulted with an infinite loop. So in order to make sure that's not a problem specific to for, I switched to while andthe same thing still happens. That being said, it doesn't occur if i replace ++i by i++. I unrolled the whole loop and everything seems just fine...
I'm a beginner, by the way, in case you were wondering.
A clearer way to write this would be much less error-prone:
for (i = 0; i < 16; ++i)
printf ("%d\n", (t[i] = i % 4));
Personally I'd code something that way, but I'd never recommend it. Moreover, I don't really see much benefit in condensing statements like that, especially in the most important category: execution time. It is perhaps more difficult to optimize, so performance could actually degrade when compared to simply using:
for (i = 0; i < 16; ++i)
{
t[i] = i % 4;
printf ("%d\n", t[i]);
}
Even if it is you reading your own code, you make it difficult for your future self to understand. KISS (Keep It Simple, Stupid), and you'll find code is easier to write now and just as easy to modify later if you need to.
so i've looked through here and on google and tried various forms to try and accomplish this. it doesn't seem like it should be hard. i've tried getting a value from the char, tried just using math on it since i've read that a char in C is a number to the compiler anyway. what i have is an array of 4 strings. each element is another array of 20 + 1 characters (to include the null \0) what i'm trying to do is shift the value of each character in each string by a predefined amount using a variable "decryption_shift". what i thought i was doing is using 2 for loops, one to do one string at a time, the other to change each character in the strings. i've tried using pointers, tmp variables. yes this is a homework assignment, problem is it's a higher level class and they aren't teaching us methods/functions/syntax, they want us to research and learn on our own how to do it. i've already spent 2 hours trying to figure out this one snippet and don't know where else to turn. any help is greatly appreciated.
~justin
void decrypt_chunks()
{
for (m = 0; m < 0; m++)
{
for (n = 0; n < 20; n++)
{
// int *chunksp = &chunks[m][n];
chunks[m][n] = chunks[m][n] - DECRYPTION_SHIFT;
// *chunksp[m][n]=tmp;
// chunks[m][n]=tmp;
}
}
}
Your problem is here:
for (m = 0; m < 0; m++)
The loop will never execute because the termination condition is met on initialization. Try
for (m = 0; m < 4; m++)
I can't see where DECRYPTION_SHIFT or chunks is defined (and initialized), so make sure you're actually define it globally or in the decrpyt_chunks() function (note: usually you write variables lowercase and macros uppercase, and if DECRYPTION_SHIFT is a variable you should write it in lowercase letters)
for (m = 0; m < 0; m++) while never run, this statement in words would be something like: set m to ziro (btw where did you defined m?) and do the following things as long as m is less than ziro (never the case, as you set it to ziro)
As this seems like a very basic problem, make sure you actually understand what a programming language is and how it works and consider reading one or two books about c (or almost any other programming language, as this homework would be in most modern languages pretty much the same).
To really make this thing interresting, what you basically do is encrypting like Caesar, so to implement this, the code could look similar to this one:
#include <stdio.h>
#include <string.h>
void decrypt_chunks(int decryption_shift);
char chunks[4][21];
int main(int stdr, char *stdv[])
{
strcpy(chunks[0],"Hello World! And Bye");
printf("message string: %s\n", chunks[0]);
decrypt_chunks(1);
printf("encrypted string: %s\n", chunks[0]);
decrypt_chunks(-1);
printf("decrypted sring: %s\n", chunks[0]);
}
void decrypt_chunks(int decryption_shift)
{
for (int m = 0; m < 4; m++)
{
for (int n = 0; n < 20; n++)
{
chunks[m][n] = chunks[m][n] - decryption_shift;
}
}
}
I'm actually writing about the same program as before, but I feel like I've made significant progress since the last time. I have a new question however; I have a function designed to store the frequencies of letters contained within the message inside an array so I can do some comparison checks later. When I ran a test segment through the function by outputting all of my array entries to see what their values are, it seems to be storing some absurd numbers. Here's the function of issue:
void calcFreq ( float found[] )
{
char infname[15], alpha[27];
char ch;
float count = 0;
FILE *fin;
int i = 0;
while (i < 26) {
alpha[i] = 'A' + i++;
}
printf("Please input the name of the file you wish to scan:\n");
scanf("%s", infname);
fin = fopen ( infname, "r");
while ( !feof(fin) ) {
fscanf(fin, "%c", &ch);
if ( isalpha(ch) ) {
count += 1;
i = 0;
if ( islower(ch) ) { ch = toupper(ch); }
while ( i < 26 ) {
if ( ch == alpha[i] ) {
found[i]++;
i = 30;
}
i++;
}
}
}
fclose(fin);
i = 0;
while ( i < 26 ) {
found[i] = found[i] / count;
printf("%f\n", found[i]);
i++;
}
}
At like... found[5], I get this hugely absurd number stored in there. Is there anything you can see that I'm just overlooking? Also, some array values are 0 and I'm pretty certain that every character of the alphabet is being used at least once in the text files I'm using.
I feel like a moron - this program should be easy, but I keep overlooking simple mistakes that cost me a lot of time >.> Thank you so much for your help.
EDIT So... I set the entries to 0 of the frequency array and it seems to turn out okay - in a Linux environment. When I try to use an IDE from a Windows environment, the program does nothing and Windows crashes. What the heck?
Here are a few pointers besides the most important one of initializing found[], which was mentioned in other comments.
the alpha[] array complicates things, and you don't need it. See below for a modified file-read-loop that doesn't need the alpha[] array to count the letters in the file.
And strictly speaking, the expression you're using to initialize the alpha[] array:
alpha[i] = 'A' + i++;
has undefined behavior because you modify i as well as use it as an index in two different parts of the expression. The good news is that since you don't need alpha[] you can get rid of its initialization entirely.
The way you're checking for EOF is incorrect - it'll result in you acting on the last character in the file twice (since the fscanf() call that results in an EOF will not change the value of ch). feof() won't return true until after the read that occurs at the end of the file. Change your ch variable to an int type, and modify the loop that reads the file to something like:
// assumes that `ch` is declared as `int`
while ( (ch = fgetc(fin)) != EOF ) {
if ( isalpha(ch) ) {
count += 1;
ch = toupper(ch);
// the following line is technically non-portable,
// but works for ASCII targets.
// I assume this will work for you because the way you
// initialized the `alpha[]` array assumed that `A`..`Z`
// were consecutive.
int index = ch - 'A';
found[index] += 1;
}
}
alpha[i] = 'A' + i++;
This is undefined behavior in C. Anything can happen when you do this, including crashes. Read this link.
Generally I would advise you to replace your while loops with for loops, when the maximum number of iterations is already known. This makes the code easier to read and possibly faster as well.
Is there a reason you are using float for counter variables? That doesn't make sense.
'i = 30;' What is this supposed to mean? If your intention was to end the loop, use a break statement instead of some mysterious magic number. If your intention was something else, then your code isn't doing what you think it does.
You should include some error handling if the file was not found. fin = fopen(..) and then if(fin == NULL) handle errors. I would say this is the most likely cause of the crash.
Check the definition of found[] in the caller function. You're probably running out of bounds.