I'm new to C and I've got a question about arrays.
I need to display an array, containing numbers, easy enough. Then, the troubling part, the user is supposed to enter a value, which represents the ranking of the values in the array, think of it like a list of prices, the lower the entered number, the smaller the printed out number is, and I've got no clue how to do it.
I've tried a bubble sort, which sorts all the numbers in the array, but then what?
For example, the array is 10, 1000, 50 if the user enters 1, they would get 10, the smallest, if they enter 3, they'd get 1000.
Here is the code I stole straight from some website, all this does is arrange the array in a bubble sort
#include <stdio.h>
void swap(int *xp, int *yp)
{
int temp = *xp;
*xp = *yp;
*yp = temp;
}
// A function to implement bubble sort
void bubbleSort(int arr[], int n)
{
int i, j;
for (i = 0; i < n-1; i++)
// Last i elements are already in place
for (j = 0; j < n-i-1; j++)
if (arr[j] > arr[j+1])
swap(&arr[j], &arr[j+1]);
}
/* Function to print an array */
void printArray(int arr[], int size)
{
int i;
for (i=0; i < size; i++)
printf("%d ", arr[i]);
printf("\n");
}
// Driver program to test above functions
int main()
{
int arr[] = {25000, 10000, 25000, 90000, 90000, 25000, 25000, 10000, 10000, 25000};
int n = sizeof(arr)/sizeof(arr[0]);
bubbleSort(arr, n);
printf("Sorted array: \n");
printArray(arr, n);
return 0;
}
Any help is appreciated.
Related
Baby programmer here! I am stumped. I need help with an assignment and as concluded in my last question, my professor is no help, and I have done lots of research and I cannot find any examples or answers in my book or YouTube. In C, I have to use a loop to load random integer values into a 1 dimensional array and a multidimensional array, and use functions to print the contents of each array. I've taught myself how to load random integers into a 1 dimensional array, but I'm having trouble figuring out how to call it to a function to print the results. Similarly, I can create a multidimensional array and print the results through a function, but I can't figure out how to make the integers in a multidimensional array random.
Here is what I've created and understand so far (It is a MESS and I thank you for patience in advance):
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void printArray(int a[], size_t size); //prototype
void printArray(int b[2][3]); //prototype
int main(void)
{
int n[10]; // n is an array of 10 integers
int i;
srand(time(NULL)); //uses time to make integers random
printf("One-Dimensional Array\n");
for (i = 0; i < 10; i++) //loop 10 times
{
n[i] = i + 1;
printf("%d ", (rand() % 50) + 1); //print random int from 1-100
}
printf("\nMulti-Dimensional Array\n");
int array1[2][3] = { {1, 2, 3}, {4, 5, 6} };
printArray(array1);
}
void printArray(int a[], size_t size)
{
//insert function for printing 1d array
}
void printArray(int b[][3])
{
for (size_t i = 0; i <= 1; ++i)
{
for (size_t j = 0; j <= 2; ++j)
{
printf("%d ", b[i][j]);
}
printf("\n");
}
}
Use nested loops, just like you do when printing the array.
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
array1[i][j] = rand() % 50 + 1; // random int from 1 to 50
}
}
My issue is that I am getting segmentation fault (core dumped) each time I try, I have yet to clean up my code, but I am stumped.
I must enter the values in with the compiler e.g "./filename 0 100" whereby 0 is min and 100 is max.
It must then fill the array of 10 elements with random numbers (0-100). I am so close, just can't fathom the main function.
Also, how can I print the array {0,1,2,3} in format "[0,1,2,3]" including the commas, without it looking like "[0,1,2,3, ]"
#include <stdlib.h>
#include <stdio.h>
int getRandom(int min, int max);
void fillArray(int data[], int size, int min, int max);
void printArray(int data[], int size);
int main(int argc, char *argv[]) {
int a;
int b;
if (argc>=3){
a = atoi(argv[1]);
b = atoi(argv[2]);
int arr[10];
printf("\t An array with random values from 0 to 100 \n");
fillArray(arr,10 ,a, b);
printArray(arr, 10);
} else {
printf("Incorrect number of arguments - please call with assignment min max\n");
}
return 0;
}
int getRandom(int min, int max) {
int result = 0;
int low = 0;
int high = 0;
if (min<max) {
low = min;
high = max+1;
} else {
low = max + 1;
high = min;
}
result = (rand() % (high-low)) + low;
return result;
}
void fillArray(int data[], int size, int min, int max){
int i;
for(i=min ; i < max+1; i++){
data[i] = getRandom(min,max);
}
}
void printArray(int data[], int size){
int i;
printf("[");
for(i=0; i<size; i++){
printf("%d,", data[i]);
}
printf("]");
}
I agree with #Steve Friedl that the main problem with your program lies in the fillArray function. There i should run from 0 to size.
As for your second question, testing whether you're printing the last number helps to suppress the unwanted comma:
void printArray(int data[], int size) {
printf("[");
for (int i = 0; i < size; i++) {
printf("%d", data[i]);
if (i < size - 1)
printf(",");
}
printf("]");
}
If you prefer a more compact solution (although with an optimizing compiler there's not really a difference), you could write it as:
void printArray(int data[], int size) {
printf("[");
for (int i = 0; i < size; i++) {
printf("%d%c", data[i], i < size-1 ? ',' : ']');
}
}
Also, in your main function, you should include a and b in your printing:
printf("\t An array with random values from %d to %d \n", a, b);
I believe this is blowing things up for you:
void fillArray(int data[], int size, int min, int max){
int i;
for(i=min ; i < max+1; i++){ // <-- HERE
data[i] = getRandom(min,max);
}
}
The calling function allocates 10 items in the arr array, and that's passed as the size parameter, but you're not using that parameter to limit filling up the array. If the max value is 100, then it's trying to fill one hundred slots instead of just ten.
for (i = 0; i < size; i++)
data[i] = getRandom(min,max);
should fix at least this issue.
EDIT: The comma thing, I prefer to add commas before the items unless this is the first. In this case it doesn't matter much, but it's more general, especially for variable-length lists where you don't know you're at the end until you get there. Augmenting the helpful response from #JohanC :
void printArray(int data[], int size) {
printf("[");
for (int i = 0; i < size; i++) {
if (i > 0) printf(",");
printf("%d", data[i]);
}
printf("]");
}
I am writing a program to generate all possible permutations of a given series of numbers and then generate all possible binary trees from that permutations so, what I thought is having a program which generates permutations and stores the result to a file and then write further code to read line by line (which has all permutations ) and generate binary trees out of them, so right now I have written half program which generates permutation and it stores the result in file.
#include <stdio.h>
//function to print the array
void printarray(int arr[], int size)
{
FILE *fp;
int i,j;
fp=fopen("result.txt","w");
for(i=0; i<size; i++)
{
// printf("%d\t",arr[i]);
fprintf(fp,"%d\t",arr[i]);
}
printf("\n");
fclose(fp);
}
//function to swap the variables
void swap(int *a, int *b)
{
int temp;
temp = *a;
*a = *b;
*b = temp;
}
//permutation function
void permutation(int *arr, int start, int end)
{
if(start==end)
{
printarray(arr, end+1);
return;
}
int i;
for(i=start;i<=end;i++)
{
//swapping numbers
swap((arr+i), (arr+start));
//fixing one first digit
//and calling permutation on
//the rest of the digits
permutation(arr, start+1, end);
swap((arr+i), (arr+start));
}
}
int main()
{
//taking input to the array
int size;
printf("Enter the size of array\n");
scanf("%d",&size);
int i;
int arr[size];
for(i=0;i<size;i++)
scanf("%d",&arr[i]);
//calling permutation function
permutation(arr, 0, size-1);
return 0;
}
but the problem here in this program is that this program only stores one permutation and does not stores other permutations in result.txt file, how do I go on storing result this way. Also program does not ends a blank cursor blinking which gives a false impression of infinite while loop.
I had to press Ctrl+c to end the program how to get rid of this?
your fopen("result.txt","w"); truncates file each time opened.
use fopen("result.txt","a"); instead
#include<string.h>
#include<stdio.h>
#include<stdlib.h>
#define N 10
void print(int *num, int n)
{
FILE *fp;
fp=fopen("result.txt","a");
int i;
for ( i = 0 ; i < n ; i++)
// printf("%d ", num[i]);
fprintf(fp,"%d ",num[i]);
fprintf(fp,"\n");
fclose(fp);
}
int main()
{
int num[N];
int *ptr;
int temp;
int i, n, j;
printf("\nHow many number you want to enter: ");
scanf("%d", &n);
printf("\nEnter a list of numbers to see all combinations:\n");
for (i = 0 ; i < n; i++)
scanf("%d", &num[i]);
for (j = 1; j <= n; j++) {
for (i = 0; i < n-1; i++) {
temp = num[i];
num[i] = num[i+1];
num[i+1] = temp;
print(num, n);
}
}
return 0;
}
The code does run. This is a little different version of quicksort I am working on. I am running into some major issues with it. First off It prints out the first element in the array as n: for example(if you set n = 3, even if you make the first element in the array 1 lets say, it will still print out 3 as the first element). Also when you print out the sorted version it doesn't actually change anything.
Example input with n = 3,
Set values = 8 , 7 , 6
Initial output will equal 3 , 7 , 6
Final output will equal 3 , 7 , 6
(The output SHOULD be 6 , 7 , 8)
I haven't been able to find any code online similar to my code, so this may be something new! Thanks.
//preprocessor directives and header files
#include <stdio.h>
#define MAX_ARRAY_SIZE 50
//function prototypes separated by data types
void print_array( int array[], int n ); // Print out the array values
void swap( int array[], int index1, int index2 ); // Swap two array elements.
void quicksort( int array[], int low, int high ); // Sorting algorithm
int populate_array( int array[] ); // Fill array with values from user.
int partition( int array[], int low, int high ); // Find the partition point (pivot)
//the main function
int main(void)
{
int array[MAX_ARRAY_SIZE];
//set n = to size of user created size of array
int n = populate_array(&array[MAX_ARRAY_SIZE]);
//print the original array to the screen
print_array(&array[MAX_ARRAY_SIZE], n );
//perform the algorithm
quicksort(array, 0, n-1);
printf("The array is now sorted:\n");
print_array(&array[MAX_ARRAY_SIZE], n);
return 0;
}
// *array and array[] are the same...
int populate_array(int array[])
{
int n = -1;
printf("Enter the value of n > ");
scanf("%d", &n);
if(n > MAX_ARRAY_SIZE)
{
printf("%d exceeds the maximum array size. Please try again.\n\n", n);
populate_array( &array[MAX_ARRAY_SIZE]);
}
else if(n < 0)
{
printf("%d is less than zero. Please try again.\n\n", n);
populate_array( &array[MAX_ARRAY_SIZE]);
}
else if(n == 0)
{
printf("%d Array of size 0? Please don't try this, and... Please try again.\n\n", n);
populate_array( &array[MAX_ARRAY_SIZE]);
}
else
{
for(int i = 0; i < n; i++)
scanf("%d", &array[i]);
}
printf("The initial array contains: \n");
return n;
}
void print_array(int array[], int n)
{
for(int i = 0; i < n; i++)
printf("%+5d\n", array[i]);
}
void quicksort(int array[], int low, int high)
{
if (low < high)
{
/* pivot is partitioning index, array[p] is now
at right place */
int pivot = partition(array, low, high);
// Separately sort elements before
// partition and after partition
quicksort(array, low, pivot - 1);
quicksort(array, pivot + 1, high);
}
}
int partition(int array[], int low, int high)
{
int pivot = array[high];
int i = low;
for (int j = low; j <= high- 1; j++)
{
// If current element is smaller than or
// equal to pivot
if (array[j] <= pivot)
{
swap(array, i, j);
i = i +1;
}
}
swap(array, i, high);
return i;
}
void swap(int array[], int index1, int index2)
{
int temp = array[index1];
array[index1] = array[index2];
array[index2] = temp;
}
Here is a heavily commented answer. I changed the code quite a bit.
This is now a fully functional quicksort array for user input.
The problem I was having before was with the &array[MAX_ARRAY_SIZE]. This needed to be changed to just "array" instead. The &array[MAX_ARRAY_SIZE] was trying to access a memory location past the actual size of the array.
Changing it to just "array" means that it is accessing the first element in the array.(Correct if wrong)
I also changed the populate array function to be a robust do-while loop. And instead of trying to re-call the function inside itself. The do-while loop will only allow you to change the value of 'n'.
/*
Author: Zachary Alberda
*/
//preprocessor directives and header files
#include <stdio.h>
#define MAX_ARRAY_SIZE 50
//function prototypes separated by data types
void print_array( int array[], int n ); // Print out the array values
void swap( int array[], int index1, int index2 ); // Swap two array elements.
void quicksort( int array[], int low, int high ); // Sorting algorithm
int populate_array( int array[] ); // Fill array with values from user.
int partition( int array[], int low, int high ); // Find the partition point (pivot)
//the main function
int main(void)
{
int array[MAX_ARRAY_SIZE]; //set n = to size of user created size of array
int n = populate_array(array); //print the original array to the screen
print_array(array, n ); //print array of size n
quicksort(array, 0, n-1); //perform the algorithm low is 0, high is size of array -1.
printf("The array is now sorted:\n");//Inform user that the array is sorted.
print_array(array, n);//print the sorted array
return 0; // exit without errors.
}
// *array and array[] are the same...
int populate_array(int array[])
{
int n = -1;//initialize variable n(local variable to function populate_array)
printf("Enter the value of n > ");//inform user of what to input
scanf("%d", &n);
/*
CHECK IF N IS VALID
This is a robust do while loop!
1) Performs the if-statements while 'n' is not valid in a do-while loop.
-The reason I do this is because it will cause errors
if the if-statements are individual without the do-while loop.
2)The program will not crash if you try different combinations
of inputs for 'n'. :)
3)Checks if user input is > MAX_ARRAY_SIZE
4)Checks if user input is < 0
5)Checks if user input is == 0
*/
do
{
if(n > MAX_ARRAY_SIZE)
{
printf("%d exceeds the maximum array size. Please try again.\n\n", n);
printf("Enter the value of n > ");
scanf("%d", &n);
}
else if(n < 0)
{
printf("%d is less than zero. Please try again.\n\n", n);
printf("Enter the value of n > ");
scanf("%d", &n);
}
else if(n == 0)
{
printf("%d Array of size 0? Please don't try this, and... Please try again.\n\n", n);
printf("Enter the value of n > ");
scanf("%d", &n);
}
}while(n <= 0 || n > MAX_ARRAY_SIZE);
//scan in array if user input is valid
for(int i = 0; i < n; i++)
scanf("%d", &array[i]);
printf("The initial array contains: \n");//Inform user of initial array
return n;
}
void print_array(int array[], int n)
{
//print array in pre/post order before and after the algorithm.
for(int i = 0; i < n; i++)
printf("%+5d\n", array[i]);
}
void quicksort(int array[], int low, int high)
{
if (low < high)
{
/* pivot is partitioning index, array[pivot] is now
at right place */
int pivot = partition(array, low, high);
// Separately sort elements before
// partition and after partition
quicksort(array, low, pivot - 1);
quicksort(array, pivot + 1, high);
}
}
int partition(int array[], int low, int high)
{
int pivot = array[high];
int i = low;
for (int j = low; j <= high- 1; j++)
{
// If current element is smaller than or
// equal to pivot
if (array[j] <= pivot)
{
swap(array, i, j);
i = i +1;
}
}
swap(array, i, high);
return i;
}
void swap(int array[], int index1, int index2)
{
//swap positions of array index 1 and 2
int temp = array[index1];
array[index1] = array[index2];
array[index2] = temp;
}
I'm a beginner in C and I've been trying to code a Quicksort program that can take a randomly generated array of real numbers and its size as its argument, and then sorts the elements in ascending order. I cannot figure out what to put in the array size field in the first recursive call of the function QuickSort, which is meant to represent the subarray A[0...q-1]. As far as I can tell, the rest of the code is fine because when linked to a driver program that generates the random numbers, the program returns the elements, albeit in the incorrect order. I appreciate any help/suggestions.
int Partition(float *,int);
int QuickSort(float *A,int n)
{
int q;
if(n>1){
q = Partition(A,n);
QuickSort(&A[],q); //Trying to figure out what to put in here.
QuickSort(&A[q+1],(n-1)-q); //This recursion sends the subarray A[q+1...n-1] to QuickSort, I think it works fine.
}
}
int Partition(float *A,int n){
int i,j;
float x;
x = A[n-1];
i=0;
for(j=0;j<=n-2;j++){
if(A[j] <= x){
A[i]=A[j];
i = i+1;
}
}
A[i]=A[n-1];
return i;
}
You're only problem is you seem to confuse:
A[i]=something;
with swapping A[i] and something. Add an auxiliary tmp, or write a swap function:
#include<stdio.h>
int Partition(float *,int);
void QuickSort(float *A,int n) {
int q;
if(n>1){
q = Partition(A,n);
QuickSort(A,q); //Trying to figure out what to put in here.
QuickSort(A+q+1,(n-q-1)); //This recursion sends the subarray A[q+1...n-1] to QuickSort, I think it works fine.
}
}
int Partition(float *A,int n){
int i,j;
float x;
float tmp;
x = A[n-1];
i=0;
for(j=0;j<=n-2;j++){
if(A[j] <= x){
tmp = A[i];
A[i]=A[j];
A[j]=tmp;
i = i+1;
}
}
tmp = A[i];
A[i]=A[n-1];
A[n-1]=tmp;
return i;
}
int main() {
float A[] = {3, 4, -5, 10, 21, -9, -1, 7, 8, 10};
QuickSort(A,10);
for(int i = 0; i < 10; i ++)
printf("%f ",A[i]);
return 0;
}