I am trying to run this code on Dev C++ but it keeps on crashing after the user inputs the two numbers. The program takes input m and n from user two numbers and then returns the output as the solution of the function A which is:
A(m,n) = A(m,n-1)+ A(m-1, n) , if m,n >0
A(m,n) = m-n if m or n <0
Can anybody please tell me why is it happening?
#include<stdio.h>
#include<stdlib.h>
int main() {
int num1=0;
int num2=0;
int rows=0;
int columns=0;
int i,j,**array;
printf("Enter two non-negative integer numbers \n");
scanf("%d %d",&num1,&num2);
//create 2d-Array
rows=num1+1;
columns=num2+1;
array=malloc(rows * sizeof(int *));
for(i=0;i<rows;i++)
{
array[i]=malloc(columns*sizeof(int));
}
//Fill data in array
computeArray(array,rows,columns);
// Display contents of array
for (i = 0; i < rows; i++ )
{
for(j= 0; j < columns; j++ )
{
printf("array[%d][%d] = %d\n", i,j, array[i][j] );
}
}
getch();
return 0;
}
int computeArray (int **array, int rows, int columns) {
int i,j;
for(i=0; i<rows;i++)
{
for(j=0;j<columns;j++)
{
array[i][j]=computeFunction(array,i,j);
}
}
return **array;
}
int computeFunction(int **array, int i, int j) {
int value=0;
if((i<0)||(j <0))
{
value = i-j;
printf("%d",value);
return value;
}
else
{
value = (array[i][j-1] + array[i-1][j]);
printf("%d",value);
return value;
}
return value;
}
When program's behavior is undefined, anything could happen. You should declare a prototype for the function computeArray and computeFunction before main:
int computeArray (int **array, int rows, int columns);
int computeFunction(int **array, int i, int j);
and change
if((i<0)||(j <0)) {...}
in computeFunction to
if((i<=0) || (j <= 0)){...}
&& instead of || may help.
The code fails at the
value = (array[i][j-1] + array[i-1][j]);
line, when j==0.
Debuggers tend to be very useful for spotting simple mistakes. Use them.
Related
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 defined a matrix into a function. how do i return that matrix for print it when i call it with another function. i mean...
#include<stdio.h>
#include<conio.h>
#include<time.h>
void main() {
int m,n;
printf("type 2 numbers:");
scanf("%i %i",&m,&n);
declaration(m,n);\\HERE IS THE PROBLEM
printing(matrix,m,n);
getch();
}
void declaration(int a,int b) {
srand(time(NULL));
int i,j,matrix[a][b];
for(i=0;i<a;i++){
for(j=0;j<b;j++){
matrix[i][j]=1+rand()%7;
}
}
}
void printing(int c[100][100],int a,int b) {
int i,j;
for(i=0;i<a;i++){
for(j=0;j<b;j++){
printf("%i\t",c[i][j]);
}
printf("\n");
}
}
Define it like:
typedef struct {
int rows;
int cols;
int *data;
} int_matrix_entity, *int_matrix;
int_matrix int_matrix_create(int rows, int cols, bool rand)
{
int_matrix mt;
int i;
if ((mt = malloc(sizeof(int_matrix_entity))) == NULL)
{
return NULL;
}
if ((mt->data = malloc(sizeof(int) * cols * rows)) == NULL)
{
free(mt);
return NULL;
}
if (rand)
{
srand(time(NULL));
for (i = 0; i < cols * rows; i++)
{
mt->data[i] = 1 + rand() % 7;
}
}
else
{
memset(mt->data, 0, sizeof(int) * cols * rows);
}
return mt;
}
void int_matrix_printf(int_matrix mt)
{
int i;
int j;
for (i = 0; i < mt->rows; i++)
{
for (j = 0; j < mt->cols; j++)
{
printf("%5d ", mt[i * cols + j]);
}
printf("\n");
}
}
You have a few points that require a bit more attention;
1 ) read warning and error messages given by your compiler
2 ) again, read warning messages given by your compiler
3 ) use indentation to make your code more readable.
4 ) Always return from main(), that's a good practice
The code below does what you want to achieve; have a look at it and keep on reading...
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
// You either have to declare your functions
// or implement them before main()
void declaration(int a,int b, int m[a][b]);
void printing(int a,int b, int m[a][b]);
int main(){ // always return from main()
int m,n;
printf("type 2 numbers:");
scanf("%i %i",&m,&n);
int matrix[m][n];
declaration(m, n, matrix);
printing(m, n, matrix);
return 0;
}
void declaration(int a,int b, int m[a][b]){
srand(time(NULL));
int i,j;
for(i=0;i<a;i++){
for(j=0;j<b;j++){
m[i][j]=1+rand()%7;
}
}
}
void printing(int a,int b, int m[a][b]){
int i,j;
for(i=0;i<a;i++){
for(j=0;j<b;j++){
printf("%i\t",m[i][j]);
}
printf("\n");
}
}
You need a way to transfer data from one function to another. You cannot simply declare an auto variable in one function and pass it to another as you did in the code below
declaration(m,n);
printing(matrix,m,n); /* where does matrix[][] come from? */
remember, C is a strongly typed language which means you have to declare your variables before using them. This applies to your functions as well. You either have to give your function declarations before main() (or more specifically, before using them), or implement them.
Look into your header files (i.e. .h files) and you will see lots of function declarations.
Since you use variable length arrays, make sure your compiler is at least capable of compiling code confirming C99 standard.
Some extras;
Normally, C passes arguments by value and you have to use a pointer if you want the value of your variable get changed within the function. If you have a close look at the code snippet I gave, I simply used an int m[a][b].In C, the name of an array is a pointer to its first element, hence you can change the value of array elements when actually array's name is passed to your function as an argument.
For further reading, you may want to look at
variable scope
global variables (you can define matrix[][] as a global variable and change the value of matrix elements)
declaration vs definition in C
Another simple way to do it is use double pointer to create 2-dimensional array. Keep it simple.
#include <stdio.h>
#include <stdlib.h>
int** create_matrix(int rows, int cols) {
int **matrix = malloc(rows*(sizeof(int *)));
for(int i = 0; i < rows; i++) {
matrix[i] = malloc(cols*sizeof(int));
}
for(int i = 0; i < rows; i++) {
for(int j = 0; j < cols; j++) {
matrix[i][j] = 1 + rand()%7;
}
}
return matrix;
}
void printing(int** matrix, int rows, int cols) {
for(int i = 0; i < rows; i++) {
for(int j = 0; j < cols; j++) {
printf("%d ", matrix[i][j]);
}
printf("\n");
}
}
int main(void) {
int rows, cols;
rows = 3, cols = 3;
int** matrix = create_matrix(rows, cols);
printing(matrix, rows, cols);
free(matrix);
return 0;
}
Ok I need to write two functions iterative and recursive to count negative elements in an array and then I need to build main. I was only able to write the recursive function but I cannot call it from main, it is an error somewhere. Can someone help me out solve it and help me with the iterative method?
#include <stdio.h>
main()
{
int vektor[100];
int i, madhesia;
/* Input size of array */
printf("Madhesia e vektorit: ");
scanf("%d", &madhesia);
/* Input array elements */
printf("Elementet: ");
for (i = 0; i < madhesia; i++)
{
scanf("%d", &vektor[i]);
}
int ret = numero(vektor, madhesia);
printf("\nTotal negative elements in array = %d", ret);
return 0;
}
int numero(array, size)
{
int count = 0;
for (int j = 0; j < size; j++)
{
if (array[j] < 0)
{
count++;
}
}
return count;
}
A working piece of code is this.You really need to take a look at pointers and the way they work.
Here you can see that I have a pointer ->pointing-< at the start of the array , so by passing the starting address of the array , and the length of the array , your functions knows what it is needed to be done.
#include <stdio.h>
int numero(int* array, int size);
int* recursive_count(int* array, int size , int* counter );
int main()
{
int vektor[100];
int* vekt_ptr = &vektor[0];
int i, madhesia;
int counter;
counter=0;
/* Input size of array */
printf("Madhesia e vektorit: ");
scanf("%d", &madhesia);
/* Input array elements */
printf("Elementet: ");
for (i = 0; i < madhesia; i++)
{
scanf("%d", &vektor[i]);
}
//int ret = numero(vekt_ptr, madhesia);
recursive_count(vekt_ptr, madhesia , &counter );
int ret = counter;
printf("\nTotal negative elements in array = %d", ret);
return 0;
}
int numero(int* array, int size)
{
int count = 0;
int j;
for (j = 0; j < size; j++)
{
if (array[j] < 0)
{
count++;
}
}
return count;
}
int* recursive_count(int* array, int size , int* counter )
{
size--;
if(array[size] < 0 )
{
(*counter)++;
}
if(size==0)
{
return NULL;
}
return recursive_count(array++, size , counter );
}
Let's assume that you want to create dynamically an array of X length.
The compiler is going to have some memory for your array , depending on the length.
You initialize your array , lets say [2][45][1][-5][99]
When you call the function you have to pass where this is stored in memory.
int* vekt_ptr = &vektor[0]; -s going to give as something like 0x56c2e0.
This number is the address of your array , which is the address of the starting point of the array.This is equal with the address of first byte.
So when your function starts , it knows where your array starts and how long it is.
For starters according to the C Standard the function main without parameters shall be declared like
int main( void )
Any function used in a program shall be declared before its usage.
This function declaration of the function definition
int numero(array, size)
{
// ...
}
is invalid because the types of the parameters array and size are undefined.
For the size of an array and for the count of elements it is better to use an unsigned integer type like for example size_t or at least unsigned int.
The program can look the following way
#include <stdio.h>
#define N 100
size_t iterative_numero( const int array[], size_t size );
size_t recursive_numero( const int array[], size_t size );
int main( void )
{
int vektor[N];
size_t madhesia = 0;
/* Input size of array */
printf("Madhesia e vektorit: ");
scanf("%zu", &madhesia);
if ( N < madhesia ) madhesia = N;
/* Input array elements */
printf("Elementet: ");
for ( size_t i = 0; i < madhesia; i++ )
{
scanf( "%d", &vektor[i] );
}
size_t ret = iterative_numero(vektor, madhesia );
printf("\nTotal negative elements in array = %zu\n", ret);
ret = recursive_numero(vektor, madhesia );
printf("Total negative elements in array = %zu\n", ret);
return 0;
}
size_t iterative_numero( const int array[], size_t size )
{
size_t count = 0;
for ( size_t i = 0; i < size; i++)
{
if ( array[i] < 0 )
{
count++;
}
}
return count;
}
size_t recursive_numero( const int array[], size_t size )
{
return size == 0 ? 0 : ( array[0] < 0 ) + recursive_numero( array + 1, size - 1 );
}
the program output might look like
Madhesia e vektorit: 10
Elementet: 0 -1 2 -3 4 -5 6 -7 8 -9
Total negative elements in array = 5
Total negative elements in array = 5
First of all what you did is the iterative method, not recursive. Here I have called a recursive function from the main function.
#include <stdio.h>
int main()
{
int vektor[100];
int i, madhesia;
/* Input size of array */
printf("Madhesia e vektorit: ");
scanf("%d", &madhesia);
/* Input array elements */
printf("\nElementet: ");
for (i = 0; i < madhesia; i++)
{
scanf("%d", &vektor[i]);
}
printf("\nno of elements:%d",madhesia);
printf("\n");
for (i = 0; i < madhesia; i++)
{
printf("%d", vektor[i]);
}
printf("\n");
i=0;
int ret = numero(vektor,madhesia,0,i);
printf("\nTotal negative elements in array = %d", ret);
return 0;
}
int numero(int array[],int size,int count,int j)
{
if (j<=size-1)
{
if(array[j]<0)
{
count++;
j++;
numero(array,size,count,j);
}
else
{
j++;
numero(array,size,count,j);
}
}
return count;
}
Put function prototype of numero() before main() to be able to call it. Declare function parameters with type:
int numero(int array[], int size);
int main() {
...
#include<stdio.h>
int numero(int *, int); //Function Prototype (1)
int main() //Return Type (2)
{
int vektor[100];
int i, madhesia;
printf("Madhesia e vektorit: ");
scanf("%d", &madhesia);
printf("Elementet: ");
for (i = 0; i < madhesia; i++)
{
scanf("%d", &vektor[i]);
}
int ret = numero(vektor, madhesia);
printf("\nTotal negative elements in array = %d", ret);
return 0;
}
int numero(int* array,int size) //Parameters Data Type (3)
{
int count = 0;
for (int j = 0; j < size; j++)
{
if (array[j] < 0)
{
count++;
}
}
return count;
}
Errors:
You have declared the function after "main()" so the program doesn't know that there is a function, so you have to give the function prototype before "main()" so that the program knows there is function ahead.
You missed writing the return type of "main()" which is integer.
In the function declaration you forgot to write the data type of the parameters.
NOTE: The array is always passed by reference so it has to taken in an integer pointer instead of a normal integer.
Some possible implementations:
int iterativeCountNegativeIntegers (int *array, int size)
{
int result = 0;
for (int i = 0; i < size; ++ i)
if (array[i] < 0)
result += 1;
return result;
}
int recursiveCountNegativeIntegers (int *array, int size)
{
if (size == 0)
return 0;
int partial = *array < 0;
return partial + recursiveCountNegativeIntegers(array+1, size-1);
}
The same, condensed:
int iterativeCountNegativeIntegers_1 (int *array, int size)
{
int result = 0;
while (--size >= 0)
result += *array++ < 0;
return result;
}
int recursiveCountNegativeIntegers_1 (int *array, int size)
{
return (size == 0) ? 0
: (*array < 0) + recursiveCountNegativeIntegers_1(array+1, size-1);
}
can you help me with code which returns partial sum of 'X' numbers in array in c?
Complete :
int arr_sum( int arr[], int n )//Recursive sum of array
{
if (n < 0) //base case:
{
return arr[0];
}
else
{
return arr[n] + arr_sum(arr, n-1);
}
}
void sum_till_last (int *ar,int si )
{
**int sum,i;// the problem some where here
ar=(int*) malloc(si*sizeof(int));
for (i=0; i<si;i++)
{
sum=arr_sum(ar,i);
ar [i]=sum;
}
free (ar);**
}
void main ()
{
int i;
int a [5];
for (i = 0; i < 5; i++)
scanf_s("%d", &a[i]);
sum_till_last(a,5);
printf("%d\n",a[5]);
}
\i want to create new array with this this legality:
My input :
4
13
23
21
11
The output should be (without brackets or commas):
4
17
40
61
72
Now when we can see the full code, it's quite obvious that the problem is in the sum_till_last function where you overwrite the pointer you pass to the function with some new and uninitialized memory you allocate.
Drop the allocation (and the call to free of course). And fix the logical bug in arr_sum that causes you to get arr[0] + arr[0] when i is zero.
Here you go:
#include <stdio.h>
int main () {
int in_arr[5] = {4,13,23,21,11};
int out_arr[5];
int p_sum =0;
int i;
for ( i=0;i<5;i++){
out_arr[i] = in_arr[i]+p_sum;
p_sum=p_sum+in_arr[i];
}
for (i=0;i<5;i++){
printf("%d", out_arr[i] );
}
}
Fix according to your policy
#include <stdio.h>
#include <stdlib.h>
int arr_sum(int arr[], int n){
if (n == 0){//Change to this
return arr[0];
} else {
return arr[n] + arr_sum(arr, n-1);
}
}
void sum_till_last(int *ar, int si){
int sum,i;
int *temp = malloc(si * sizeof(int));//variable name ar is shadowing parameter name ar.
for(i = 0; i < si; i++){
temp[i] = arr_sum(ar, i);
if(i)
putchar(' ');
printf("%d", temp[i]);//need print out :D
}
free(temp);
}
int main(void){
int i, a[5];
for (i = 0; i < 5; i++)
scanf_s("%d", &a[i]);
sum_till_last(a, 5);
//printf("%d\n",a[5]);<-- this print only one element. and It's out of bounds element XD
}
I just made it simple so it´s easy to understand :)
I´m assuming "n" is always equal or less then array element number. Then you just print the SUM.
#include <stdio.h>
int arr_sum( int arr[], int n ){
int i=0,SUM=0;
for(; i < n;i++){
SUM= SUM+ arr[i];
printf("%d ",SUM);
}
}
int main(void) {
int array[] = {4, 13, 23, 21, 11};
arr_sum(array,5);
return 0;
}
I am trying to find the max number in an array. I have created a function and I am using the following code:
int maxValue( int myArray [], int size)
{
int i, maxValue;
maxValue=myArray[0];
//find the largest no
for (i=0;i)
{
if (myArray[i]>maxValue)
maxValue=myArray[i];
}
return maxValue;
}
However I get a syntax error before ) token. What am I doing wrong and am I even doing this right? Any help would be greatly appreciated.
You must pass a valid array with at least one member to this function:
#include<assert.h>
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int
maxValue(int myArray[], size_t size) {
/* enforce the contract */
assert(myArray && size);
size_t i;
int maxValue = myArray[0];
for (i = 1; i < size; ++i) {
if ( myArray[i] > maxValue ) {
maxValue = myArray[i];
}
}
return maxValue;
}
int
main(void) {
int i;
int x[] = {1, 2, 3, 4, 5};
int *y = malloc(10 * sizeof(*y));
srand(time(NULL));
for (i = 0; i < 10; ++i) {
y[i] = rand();
}
printf("Max of x is %d\n", maxValue(x, sizeof(x)/sizeof(x[0])));
printf("Max of y is %d\n", maxValue(y, 10));
return 0;
}
By definition, the size of an array cannot be negative. The appropriate variable for array sizes in C is size_t, use it.
Your for loop can start with the second element of the array, because you have already initialized maxValue with the first element.
A for loop has three parts:
for (initializer; should-continue; next-step)
A for loop is equivalent to:
initializer;
while (should-continue)
{
/* body of the for */
next-step;
}
So the correct code is:
for (i = 0; i < size; ++i)
the paren after the for seems to be missing some contents.
normally it should be something like
for (i=0; i<size; i++)
include:
void main()
{
int a[50], size, v, bigv;
printf("\nEnter %d elements in to the array: ");
for (v=0; v<10; v++)
scanf("%d", &a[v]);
bigv = a[0];
for (v=1; v<10; v++)
{
if(bigv < a[v])
bigv = a[v];
}
printf("\nBiggest: %d", bigv);
getch();
}