void checker(int width,int height){
int horizontal;
int repeat;
int i;
int j;
for(j=1; j<=height; j++){
while(horizontal<=width){
repeat = width/10;
if(horizontal%2){
for(i = 1; i <=repeat; i++)
printf("1");
}
else{
for(i = 1; i <=repeat; i++)
printf("0");
}
horizontal++;
}
printf("\n");
}
}
int main(){
checker(20,10);
return 0;
}
So I'm creating a pattern through C. As you can tell from my code, I'm barely getting the hang of C. As I compile and test this the pattern doesn't print out in 0's and 1's, rather it only prints the \n.
I was wondering why, I might be having a brain fart.
Thank you for the time, it's very appreciated from new comers like me!
Horizontal is not properly initialized. Right now you are using garbage value left in memory. Give horizontal a proper value before trying to use it.
horizontal has not been initialized. unlike some languages, C will not default a non static local variable to 0. It will be just whatever value happens to be in memory.
Change/add line(s):
int horizontal;//not guaranteed to be zero
to
int horizontal = 0;//guaranteed to be zero
Otherwise, this statement may never enter the brackets
while(horizontal<=width){ ...
Also (not required, but maybe nice to have) add this line just after int j;...
...
int j;
if((width < 0) || (height < 0)) return; //prevent negative input values
Related
I have an assignment from my uni where I have to print a triangle using recursion in C language. I have tried writing my code as follows but I am not able to find my mistake. Kindly can anyone point out where I have to edit.
int tri(int x, int org);
int dreick(int x) {
return tri(x,x);
}
int tri(int x,int org) {
if (x == 0) {
return 0;
}
else {
return (x - 1, org);
}
for (int i = 0; i < (org - x); i++) {
printf("");
}
for (int j = 0; j <= x; j++) {
printf("*");
}printf("\n");
}
int main() {
int a = dreick(5);
printf("%d",a);
}
Recursion works as follows: each step receives a parameter which specifies what work still needs to be done; if no work needs to be done, then it returns without doing anything; otherwise, it does one step of the work, and then invokes itself with a new value for the parameter which specifies the remaining work to be done.
In your case, the parameter specifying what work still needs to be done can be the row number.
Your triangle-printing code can print the top (single star at row 0) and the bottom (row of stars at row N) outside of recursion, so as to keep things simple. Use recursion to print each line of text from 1 to N-1.
On each step of the recursion you print a number of spaces, an asterisk, some more spaces, and then another asterisk. The number of spaces depends on the row number. (How deep down the triangle you are.) You are done when you reach N-1.
I am trying to implement Insertion sort algorithm in C.
But all I get is SIGSEGV error in online IDEs and the output doesn't show up in Code::Blocks. How to avoid Such errors.
#include <stdio.h>
#include <stdlib.h>
int main()
{
/* Here i and j are for loop counters, temp for swapping
count for total number of elements,array for elements*/
int i, j, temp, count;
printf("How many numbers are you going to enter");
scanf("%d", &count);
int n[20];
printf("Enter %d elements", count);
// storing elements in the array
for(i = 0; i < count; i++) {
scanf("%d", n[i]);
}
// Implementation of insertion sort algorithm
for(i = 0; i < count; i++) {
temp = n[i];
j = i - 1;
while(temp < n[j]) {
n[j+1] = n[j];
j = j - 1;
}
n[j+1] = temp;
}
printf("Order of sorted elements");
for(i = 0; i < count; i++) {
printf("%d", n[i]);
}
return 0;
}
There are a couple of problems with your code. First of all, what is a SIGSEGV error? Well, it's another name for the good old Segmentation fault error, which is basically the error you get when accessing invalid memory (that is, memory you are not allowed to access).
tl;dr: change scanf("%d",n[i]); to scanf("%d",&n[i]);. You're trying to read the initial values with scanf("%d",n[i]);, this raises a segmentation fault error because scanf expects addresses in which put the values read, but what you're really doing is passing the value of n[i] as if it were an address (which it's not, because, as you did not set any value for it yet, it's pretty much just memory garbage). More on that here.
tl;dr: change int n[20]; to int n[count]. Your array declaration int n[20]; is going to store at most 20 integers, what happens if someone wants to insert 21 or more values? Your program reserved a certain stack (memory) space, if you exceed that space, then you're going to stumble upon another program's space and the police (kernel) will arrest you (segmentation fault). Hint: try inserting 21 and then 100 values and see what happens.
tl;dr: change for(i = 0; i < count; i++) { to for(i = 1; i <= count; i++) {. This one is a logic problem with your indexes, you are starting at i = 0 and going until i = count - 1 which would be correct in most array iteration cases, but as j assumes values of indexes before i, you need i to start from 1 (so j is 0, otherwise j = -1 in the first iteration (not a valid index)).
My final code is as follows. Hope it helped, happy coding!
#include <stdio.h>
#include <stdlib.h>
int main() {
/*Here i and j are for loop counters,temp for swapping
count for total number of elements,array for elements*/
int i, j, temp, count;
printf("How many numbers are you going to enter?\n");
scanf("%d",&count);
int n[count];
printf("Enter %d elements\n",count);
//storing elements in the array
for(i = 0; i < count; i++) {
scanf("%d", &n[i]);
}
//Implementation of insertion sort algorithm
for(i = 1; i <= count; i++) {
temp = n[i];
j = i-1;
while(temp < n[j]) {
n[j+1] = n[j];
j--;
}
n[j+1] = temp;
}
printf("Order of sorted elements\n");
for(i = 0; i < count; i++) {
printf("%d\n",n[i]);
}
return 0;
}
Edit: If you're having trouble with online IDEs, consider running your programs locally, it saves a lot of time, plus: you never know what kernel version or magic the online IDEs are using to run your code (trust me, when you're coding in C -- fairly low level language, these things make a difference sometimes). I like to go all root style using Vim as text editor and gcc for compiling as well as gdb for debugging.
My program should take a number from the user, and find the two numbers in an array such that the sum of their squares equals the user input squared. However, I'm having trouble doing this, as well as understanding all the errors I'm getting.
Here's my current attempt:
#include <stdio.h>
int numberaa;
scanf("%d",&numberaa);
int main()
{
int i,j;
int array[9] = {2,-4,6,3,9,0,-1,-9};
for (i = 0; i <= 8; i++)
for (j = 0; j <= 8; J++0)
firstone==i*i
secondone==j*j
if {
firstone+secondone=numberaa;
printf("The Numbers are %d and %d",j,i,numberaa);
return 0
};
Change
firstone+secondone=numberaa;
to
numberaa = firstone + secondone;
Ah! You need to grab a basic C book. For this time I am posting a correct code for you. Hope you will learn something.
#include <stdio.h>
int main()
{
int i,j;
int array[9] = {2,-4,6,3,9,0,-1,-9};
int numberaa;
scanf("%d",&numberaa);
for (i = 0; i <= 8; i++){
for (j = 0; j <= 8; J++0){
firstone = i*i
secondone = j*j
if(numberaa == firstone + secondone)
printf("The Numbers are %d and %d",j,i,numberaa);
}
}
return 0
}
You need to read through at least the introductory chapter of a book on C and work through the examples. That means typing them out (no, don't copy and paste), compiling them, and running them to understand what makes them work and what breaks them.
When you write your own code, always compile with warnings enabled, e.g. gcc -Wall -o my_executable_name my_code.c, and pay attention to the line numbers referenced in compiler errors and warnings.
I'll point out some locations of errors in your code below:
#include <stdio.h>
int numberaa; // Currently you're declaring this as a global. NO! not what you want.
scanf("%d",&numberaa); // This isn't going to happen out here. NO! NO NO NO!
int main() // Specify your parameters. int main(void)
{
int i,j;
int array[9] = {2,-4,6,3,9,0,-1,-9}; // why specify an array of 9 but store just 8 elements??
for (i = 0; i <= 8; i++) // These are the correct limits for array[9].
for (j = 0; j <= 8; J++0) // j and J are not the same. What is J++0 ????!! Also, read about "blocks" and try a for-loop example with more than one line.
firstone==i*i // WTF?? Have you even tried to compile this?
secondone==j*j // See line above.
if { // Likewise
firstone+secondone=numberaa; // Likewise again.
printf("The Numbers are %d and %d",j,i,numberaa); // How many formatting flags does your first argument have, and how many are to be inserted?
return 0 }; // again, have you tried to compile this?
Short version:
Semicolons
Assignment vs. equality
Scope of variables
Blocks, brace usage
syntax of if statements
You also aren't squaring the user input.
Efficiency: you only need to calculate firstone = i * i once for each i value, so take it outside the j loop.
So all I'm trying to do is take an input from the user of how many cards to use and then randomly assign each card to a different index in an array. I'm having extensive issues getting the rand function to work properly. I've done enough reading to find multiple different ways of shuffling elements in an array to find this one to be the easiest in regards to avoiding duplicates. I'm using GCC and after I input the amount of cards I never get the values from the array back and if I do they're all obscenely large numbers. Any help would be appreciated.
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
void main(){
srand(time(NULL));
int d, c, i, z, l, r;
printf("Enter the deck length: ");
scanf("%d\n ", &c);
int deck[c];
int swap[c];
z = c;
for(l=0; l<c; l++){
swap[l] = l;
}
for(i=z; i=0; i--){
r = rand() / i
deck[i] = swap[r];
for(r; r=(c-1); r++){
swap[r] = swap[(r+1)];
}
}
for(d = 0; d < c; d++){
printf("%d ", deck[d]);
}
return;
}
I can spot one major problem here:
for(i=z; i=0; i--)
^^^
This loop will never execute since you are using assignment(=) and setting i to 0 therefore the condition will always be false, although using equality(==) will still be false in this case, you probably want:
for(i=z; i!=0; i--)
This means you will be using deck unitialized which is undefined behavior. Once you fix that you have a similar problems here:
for(r; r=(c-1); r++){
main has to return int and your return at the end needs to provide a value.
Turning on warning should have allowed you to find most of these issues, for example using -Wall with gcc gives me the following warning for both for loops:
warning: suggest parentheses around assignment used as truth value [-Wparentheses]
Note, see How can I get random integers in a certain range? for guidelines on how to use rand properly.
You basically need to be able to generate 52 numbers pseudo-randomly, without repeating. Here is a way to do that...
First, loop a random number generator 52 times, with a method to ensure none of the random numbers repeat. Two functions in addition to the main() will help to do this:
#include <ansi_c.h>
int NotUsedRecently (int number);
int randomGenerator(int min, int max);
int main(void)
{
int i;
for(i=0;i<52;i++)
{
printf("Card %d :%d\n",i+1, randomGenerator(1, 52));
}
getchar();
return 0;
}
int randomGenerator(int min, int max)
{
int random=0, trying=0;
trying = 1;
while(trying)
{
srand(clock());
random = (rand()/32767.0)*(max+1);
((random >= min)&&(NotUsedRecently(random))) ? (trying = 0) : (trying = 1);
}
return random;
}
int NotUsedRecently (int number)
{
static int recent[1000];//make sure this index is at least > the number of values in array you are trying to fill
int i,j;
int notUsed = 1;
for(i=0;i<(sizeof(recent)/sizeof(recent[0]));i++) (number != recent[i]) ? (notUsed==notUsed) : (notUsed=0, i=(sizeof(recent)/sizeof(recent[0])));
if(notUsed)
{
for(j=(sizeof(recent)/sizeof(recent[0]));j>1;j--)
{
recent[j-1] = recent[j-2];
}
recent[j-1] = number;
}
return notUsed;
}
I'm trying to learn how to program in C and have stumbled into a problem that seems like it should have been a simple fix, but it's giving me more issues then I anticipated. I'm trying to created a number guessing game, where you get three chances to guess the number, but my issue is that the Do While loop wont break when the right answer is guessed. Here is the function:
void Win_Search(int lucky[],const int MAX, int user_entry, int i)
{
int j=0;
do {
j++;
printf("Please enter a number between 0 and 100\n");
scanf("%d",&user_entry);
for(i = 0; i < MAX; i++)
{
if(user_entry==lucky[i])
{
printf("winner\n");
}
}
} while(user_entry==lucky[i]||j<3);
}
Basically it's supposed to loop through the array lucky[i] and check to see if the user_entry equals any of the 20 numbers in the array. As of right now it loops through, recognizes if a winning number has been selected from the array, but doesn't break from the array.
when I change it to
}while(user_entry!=lucky[i]||j<3);
it completely ignores the counter and just loops forever.
I don't want to use break because everything I've read about it talks about it's poor programming practice. Is there another way to break, or have simply just made a mistake thats causing this issue.
Thanks in advance.
Consider for a second where your index variable "i" comes from. What happens to it after you've found a correct user entry? Where does the control flow go?
I would suggest having a look at the "break" keyword.
You wrote while (user_entry == lucky[i]..) which translates to as long as user_entry is equal to lucky[i] keep on looping. Which is clearly not what you intend to do.
Transform your condition to } while (user_entry != lucky[i] && j < 3); and you should be fine. This will translate in plain english to as long as user_entry is different of lucky[i] AND j is inferior to 3, keep looping.
But using this, you test on the value of lucky[i] even when i means nothing ( when i is equal to max, you don't want to test it, and this goes in the domain of undefined behavior).
But if you realy dont want to use break keyword, one solution is to use a flag. Set it to 1 before you start to loop, and change it to 0 when the good answer is found. Your code will become
void Win_Search(int lucky[],const int MAX, int user_entry, int i)
{
int j=0;
char flag = 1;
do {
j++;
printf("Please enter a number between 0 and 100\n");
scanf("%d",&user_entry);
for(i = 0; i < MAX; i++)
{
if(user_entry==lucky[i])
{
printf("winner\n");
flag = 0;
}
}
} while(flag&&j<3);
}
}while(user_entry!=lucky[i]||j<3);
That is bad logic - loop while the user's entry isn't the lucky number OR j is below three? Surely you actually want this:
}while(user_entry!=lucky[i]&&j<3);
This is only the solution to your second issue of it ignoring the counter - the main problem is solved in the other answers.
The only independent condition is that the user has more guesses left. try this while"
while(j <= 3);
The less than should be obvious, but the equals belongs there because you increment your j before the loop so it will be
j = 1 => first guess
j = 2 => second guess
j = 3 => third guess
After that the user should have no more guesses
You should find this doesn't work, that is because we want to exit the loop if the user guesses correctly. To do this, you can use a int as a bool (0-false, 1-yes).
void Win_Search(int lucky[],const int MAX, int user_entry, int i)
{
int j=0;
int exitCase = 0;
do {
j++;
printf("Please enter a number between 0 and 100\n");
scanf("%d",&user_entry);
for(i = 0; i < MAX; i++)
{
if(user_entry==lucky[i])
{
exitCase = 1;
printf("winner\n");
}
}
} while(exitCase == 0 || j <= 3);
}