The only elements in the array that I want are the ones that im transforming into 1, but for some reason the when im navigating trough the lower part this stack smashing occur.
```
#include <stdio.h>
#define tam 12
int main(void) {
int i, j;
int matriz[tam][tam]={{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0}};
int controle = 0, controle2 = 0;
for(i = 0; i<6;i++){
for(j=i;j<tam-i;j++){
matriz[tam-(i)][tam-(j+1)]=1;
matriz[i-1][j]=1;
}
}
for(i=0;i<tam;i++){
for(j=0;j<tam;j++){
printf("%i ", matriz[i][j]);
}
printf("\n");
}
}
```
`
```
matriz[tam-i] will resolve to matriz[12] when i = 0. This is the out of bounds write, and the source of the bug
Fixing the for(i = 0; i<6;i++) to for(i = 1; i<6;i++) should work, if that's the result you're trying to hv
Related
I'm new to C programming and I've run into a problem when creating 2D array printing function. When I try to execute the code below I get:
points.c:13: error: unknown array element size
As I've checked there are very similar codes online, which are supposed to work. I've tried to initialize function as
int print2DArray( int arrayLen, int elementLen, int array[arrayLen][elementLen])
but it raises:
points.c:3: error: 'arrayLen' undeclared
Could somebody tell me what's wrong with this code and how to fix it? I also don't understand why very similar function for 1D arrays works just fine. It has to be in pure C.
#include <stdio.h>
//supposed to print 2D array:
int print2DArray(int array[][], int arrayLen, int elementLen)
{
int i;
int j;
for (i = 0; i < arrayLen; i++)
{
for (j=0; j < elementLen; j++)
{
printf("%5d", array[i][j]);
}
printf("\n");
}
}
//prints 1D array:
int printArray( int array[], int arrayLen)
{
int i;
for (i = 0; i < arrayLen; i++)
{
printf("%d", array[i]);
}
}
--- edit ---
I undestand most of you pointed out that the function has to be called like that:
#include <stdio.h>
int print2DArray( int arrayLen, int elementLen, int array[arrayLen][elementLen])
{
int i;
int j;
for (i = 0; i < arrayLen; i++)
{
for (j=0; j < elementLen; j++)
{
printf("%5d", array[i][j]);
}
printf("\n");
}
}
This raises an error:
points.c:3: error: 'arrayLen' undeclared
I'm using tcc for windows and according to documentation it is supposed to support C99 VLA.
It appears OP's compiler (or the mode it is used) does not support variable length array (VLA) as a function parameter.
Below is a non-VLA approach.
void print2DArrayX(int arrayLen, int elementLen, const int *array) {
int i;
int j;
for (i = 0; i < arrayLen; i++) {
for (j = 0; j < elementLen; j++) {
printf("%5d", array[i*elementLen + j]);
}
printf("\n");
}
}
Call with address of first int, not the 2D array
#define ARRAY_LEN 3
#define ELEMENT_LEN 4
int array[ARRAY_LEN][ELEMENT_LEN] = { 0 };
...
print2DArrayX(ARRAY_LEN, ELEMENT_LEN, array[0]);
Ok, so thanks for all the answers - they were very helpful. I've just tried to use gcc in linux and as you've pointed out this approach works fine:
int print2DArray( int arrayLen, int elementLen, int array[arrayLen][elementLen])
I guess tcc (tiny c compiler, windows version 0.9.27) doesn't support VLA after all. A bit strange since documentation says it does.
How about you try this solution.
#include <stdio.h>
int print2DArray(int* array, int arrayLen, int elementLen)
{
int i;
int j;
for (i = 0; i < arrayLen; i++)
{
for (j=0; j < elementLen; j++)
{
printf("%5d ", *(array+j+elementLen*i));
}
printf("\n");
}
}
int main(){
int arr[2][6] = { {9,258,9,96,-8,5},
{1,1212,-3,45,27,-6}
};
print2DArray(*arr,2,6);
return 0;
}
Unless you are using a C99 compiler,
int print2DArray( int arrayLen, int elementLen, int array[arrayLen][elementLen])
is not possible.
Even if you are using C99 compiler, your code has a problem. You need to pass one of the dimension first.
int print2DArray(int arrayLen, int elementLen, int arr[][elementLen]);
So,
int print2DArray(int arrayLen, int elementLen, int arr[][elementLen])
{
// Your code
int i;
int j;
for (i = 0; i < arrayLen; i++)
{
for (j=0; j < elementLen; j++)
{
printf("%5d", array[i][j]);
}
printf("\n");
}
return 0;
}
This can be used as
int main(void)
{
int i32Array[3][3] = {{-15, 4, 36}, {45, 55, 12}, {-89, 568, -44568}};
int m = 3, n = 3;
// I am not sure why 'print2DArray' would return an int
// (or anything at all for that matter).
// If you can establish a case for it,
// modify the function and the value it is supposed to return,
// And catch it below.
print2DArray(m, n, i32Array);
return 0;
}
I am not sure how you are calling print2DArray function. Unless you post that piece of code, it is difficult to resolve your problem. Confirm that you are calling the function correctly as shown above.
I wrote some code and it showed me this error: Exception thrown at 0x00007FF93F57B016 (ucrtbased.dll) in Ficha 5.exe: 0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF.
I can't find the reason behind it.
#include <stdio.h>
#define num 10
void ler_matriz(int **matriz1, int n, int m);
void mostrar_matriz(int matriz1[num][num], int n, int m);
//int num_min_matriz(int matriz1[][], int n, int m);
//void teste_simetria(int matriz1[][], int n, int m);
//void transposta_matriz(int matriz1[][], int n, int m);
//void soma_matriz(int matriz1[][], int matriz2[][], int matriz3[][], int n, int m);
int main()
{
int x[num][num], y[num][num], z[num][num], numL, numC;
printf("Introduza o número de linhas e colunas para a matriz:\n");
scanf(" %d%d", &numL, &numC);
printf("\n\nIntroduza os valores para a matriz 1: ");
ler_matriz(x, numL, numC);
mostrar_matriz(x, numL, numC);
return 0;
}
void ler_matriz(int **matriz1, int n, int m)
{
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
printf("\nx[%d][%d]: ", i + 1, j + 1);
scanf(" %d", &matriz1[i][j]); // the exception error
}
}
}
void mostrar_matriz(int matriz1[num][num], int n, int m)
{
for (int i = 0; i < n; i++)
{
for (int j = 0; i < m; j++)
{
printf("%d ", matriz1[i][j]);
}
putchar('\n');
}
}
You have:
for (int j = 0; i < m; j++)
This should be
for (int j = 0; j < m; j++)
Otherwise, i < m is going to be true forever (because you're not changing i in that loop) and you'll eventually be accessing 0xFFFFFFFFFFFFFFFF (the very edge of memory).
For memory errors like this a good idea is to use a memory checking tool (you can try valgrind memcheck). Now let's see what's wrong with your code :)
The array
You have to take into account that int[m][n] isn't the same as int**. Using the gcc compiler you'll get a warning about it. (Of course, you can alter your code to use int**)
The For Loop
Just as VoteyDisciple said you should be using
for (int j=0;j<m;j++)
instead of
for(int j=0;i<m;j++)
Uninitialized values
Creating an array and not initializing it can lead to memory errors later on (assuming we're talking about C - some languages initialize arrays with 0's). Here you create the x,y,z matrixes but you end up using a portion of them which you assign values to. The rest remain uninitialized and you can end up running into errors if you try accessing them later on.
The scanf exception
Really the exception you get is due to the above, as you're getting errors from trying to access the memory address at &matriz1[i][j]
Fixing it all
Here's how I'd write your code so that it works:
#include <stdio.h>
#include <stdlib.h>
#define num 10
void ler_matriz(int **matriz1, int n, int m);
void mostrar_matriz(int** matriz1, int n, int m);
//int num_min_matriz(int matriz1[][], int n, int m);
//void teste_simetria(int matriz1[][], int n, int m);
//void transposta_matriz(int matriz1[][], int n, int m);
//void soma_matriz(int matriz1[][], int matriz2[][], int matriz3[][], int n, int m);
int main()
{
//int x[num][num], y[num][num], z[num][num], numL, numC;
int i,j,**x,**y,**z,numL,numC; //Proper declarations
x=malloc(num*sizeof(int*));
y=malloc(num*sizeof(int*));
z=malloc(num*sizeof(int*));
for(i=0;i<num;i++) {
x[i]=malloc(num*sizeof(int));
y[i]=malloc(num*sizeof(int));
z[i]=malloc(num*sizeof(int));
}
//Initialization
for(i=0;i<num;i++) {
for(j=0;j<num;j++) {
x[i][j]=y[i][j]=z[i][j]=0;
}
}
printf("Introduza o número de linhas e colunas para a matriz:\n");
scanf(" %d%d", &numL, &numC);
printf("\n\nIntroduza os valores para a matriz 1: ");
ler_matriz(x, numL, numC);
mostrar_matriz(x, numL, numC);
for(i=0;i<num;i++) {
free(x[i]);
free(y[i]);
free(z[i]);
}
free(x);
free(y);
free(z);
return 0;
}
void ler_matriz(int **matriz1, int n, int m)
{
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
printf("\nx[%d][%d]: ", i + 1, j + 1);
scanf(" %d", &matriz1[i][j]);
}
}
}
void mostrar_matriz(int **matriz1, int n, int m)
{
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
printf("%d ", matriz1[i][j]);
}
putchar('\n');
}
}
The program below is meant to print a square grid of integers based on the dimension which is inputted by the user (as part of the harvard cs50 course on edx).
The array is being initialized correctly, but when it comes to printing it out, the last column always prints incorrectly. I tried debugging by putting 2 printf statements in the innermost for loop of the init() function.
It seems that after the outermost loop runs once, the entry in the last column gets decremented by one, although it was correct just before this.
Why is this happening? Shouldn't it print correctly?
#include <stdio.h>
main()
{
void init(int dim, int arr[dim-1][dim-1]);
int dim;
printf("Enter board dimension(max 10): ");
scanf("%d", &dim);
int arr[dim-1][dim-1];
init(dim, arr);
int i,j;
for(i=0;i<dim;i++)
{
for(j=0;j<dim;j++)
{
printf("%2d ",arr[i][j]);
}
printf("\n");
}
}
void init(int dim, int arr[dim-1][dim-1])
{
int i,j,p;
for(i=0;i<dim;i++)
{
for(j=0;j<dim;j++)
{
arr[i][j] = (dim*dim-1)-i*dim-j;
}
for(p=0;p<dim;p++)
{
printf("%d ", arr[i][p]);
if(i>=1)
printf("%d ", arr[i-1][p]);
}
}
printf("\n");
if(dim%2==0)
{
arr[dim-1][dim-3] = 1;
arr[dim-1][dim-2] = 2;
}
}
EDIT: it should compile now
You define your array with a[dim - 1][dim - 1], which is one short of the desired dimension. If the user enters "4", you create a 3×3 array.
Your array is two-dimensional and of variable length. Therefore, you must pass the dimension alongside the array in functions, at least for the last dimension. You do this correctly, but the code in ´initbehaves as if the array werea[dim][dim], when it's actuallya[dim - 1][dim - 1]`.
Define the array with the actual dimension, dim and access the elements with indices 0 through dim - 1. This is usually done in a loop like this:
for (int i = 0; i < dim; i++) ...
Seeing >= or dim - 1 something similar should make you wary.
Your program now looks like this:
#include <stdio.h>
void init(int dim, int arr[dim-1][dim-1]);
void print(int dim, int arr[dim-1][dim-1]);
int main(void)
{
int dim;
printf("Enter board dimension: ");
scanf("%d", &dim);
int arr[dim][dim];
init(dim, arr);
print(dim, arr);
return 0;
}
void print(int dim, int arr[dim][dim])
{
int i,j;
for(i = 0; i < dim; i++) {
for(j = 0; j < dim; j++) {
printf("%2d ", arr[i][j]);
}
printf("\n");
}
}
void init(int dim, int arr[dim][dim])
{
int i, j;
for(i = 0; i < dim; i++) {
for(j = 0; j < dim; j++) {
int ii = dim - 1 - i;
int jj = dim - 1 - j;
arr[i][j] = ii*dim + jj;
}
}
}
I know this question is everywhere, but i cannot find a solution, and at this point i got pretty frustrated.
What I am trying to do is to create and use a static library. Got in the last point where i need to Build the solution, but i keep getting this error. I know the code has something, maybe more, MAYBE IS COMPLETE NONSENSE, but I can`t really see it after hours and hours trying to make it work. You know, "You cant see the forest because of the trees" W/e. Here are some screens.
#include <iostream>
#include <conio.h>
#include "matrice.h"
void din_alocation(int n, int m){
float **mat;
mat = (float**)calloc(n, sizeof(float*));
for (int i = 0; i < n; i++)
mat[i] = (float*)calloc(m, sizeof(float));
}
void read(float **mat, int n, int m){
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++) {
printf("mat[%d][%d]= ", i, j); scanf_s("%f", &mat[i][j]);
}
}
void write(float **mat, int n, int m){
for (int i = 0; i < n; i++){
printf("\n");
for (int j = 0; j < m; j++)
printf("%.2f ", mat[i][j]);
}
}
void din_realocation(float **mat, int n){
for (int i = 0; i < n; i++)
free(mat[i]);
free(mat);
}
The error should be pretty clear. You don't initialize the variable mat anywhere in the main function.
One solution is for the din_alocation function to return the data it allocates, and then do
mat = din_alocation(x, y);
I'm new here and this is my first question, i couldn't find anything like this in the search engine so my problem is basically a vector of vectors on C, here is what i have done until now but i keep getting a deadly warning, so i know that I'm not using well the structure with the vector and I'd really appreciate some help.
Thanks
PD: Sorry for my english.
#include<stdio.h>
#include<stdlib.h>
typedef struct
{
int n;
int *vector;
}Vector_T;
int inicializar_original(int *n,int dim)
{
int i,r,s,j,*k;
Vector_T *t;
Vector_T l;
srand(time(NULL));
r=rand()%10;
scanf("%d",&s);
t->vector=k;
l.n=s;
k=(int*)malloc(s*sizeof(int));
for(j=0;j<s;j++)
{
k[j]=r;
}
for(i=0;i<dim;i++)
{
n[i]=k;
}
}
int main()
{
int *v,dim;
scanf("%d",&dim);
v=(int*)malloc(dim*sizeof(int));
inicializar_original(v,dim);
}
Asumo que hablas español, así que aquí va: El problema más grande es que no estás inicializando la variable "k". Mi sugerencia es que intentes lo siguente:
int i,r,s,j;
int* k;
If English only: Your problem is probably that you're initializing K in the wrong way. Try to do:
int i,r,s,j;
int* k;
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
typedef struct {
int n;
int *vector;
}Vector_T;
int inicializar_original(Vector_T *v, int dim){
int i, j, s, r = rand()%10;
scanf("%d", &s);
for(i=0; i<dim; i++){
int *k = malloc( s * sizeof(int));
for(j=0; j<s; j++){
k[j]=r;
}
v[i].n = s;
v[i].vector = k;
}
}
int main(void){
Vector_T *v;
int dim;
srand(time(NULL));
scanf("%d", &dim);
v = malloc(dim * sizeof(*v));
inicializar_original(v, dim);
{ //check print & release
int i, j;
for(i = 0; i < dim; ++i){
for(j = 0; j < v[i].n ; ++j){
printf("%d ", v[i].vector[j]);
}
puts("");
free(v[i].vector);
}
free(v);
}
return 0;
}