I am trying to get the 10 largest files in a directory.
#include <stdio.h>
#include <ftw.h>
#include <string.h>
typedef struct File{
char path[1000];
long size;
}File;
File array_file[10];
int compt = 0;
int i = 0;
int fn(const char *fpath, const struct stat *sb, int typeflag){
switch (typeflag)
{
case FTW_F:
if(compt < 10){
strcpy(array_file[compt].path, fpath);
array_file[compt].size = sb->st_size;
compt += 1;
}
for(i; i < 10; i++){
if(sb->st_size > array_file[i].size){
printf("i am here \n");
strcpy(array_file[i].path, fpath);
array_file[i].size = sb->st_size;
}
}
break;
case FTW_D:
break;
case FTW_DNR:
return -1;
case FTW_NS:
return -1;
}
return 0;
}
this is my main :
int main(int argc, char const *argv[])
{
if(argc > 1){
ftw(argv[1], fn, 20);
}
for(int i = 0; i < 10; i++){
printf("%s\n", array_file[i].path);
printf("%ld\n", array_file[i].size);
}
return 0;
}
when i try to check the file size and replace it in my structure i get the same file in the structure 10 times.
i am new to C coding so mistakes can be made O.o, thank you for your help !
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I am learning C and I have trouble correctly using free() on char *word from my struck. The code works in its currect form but crashes if I uncomment the line in the for loop ant the end of main. How do I free it correctly?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdbool.h>
#include <errno.h>
typedef struct container
{
char *word;
int amount;
} wordContainer;
wordContainer *SetupWordList(int *size, int *lastInit, wordContainer *listIN, bool realloc);
int main(int argc, const char *argv[])
{
wordContainer *listWords = NULL;
int listSize = 10;
int listLastInit = 0;
listWords = SetupWordList(&listSize, &listLastInit, listWords, false);
for (int i = 0; i < listSize/2; i++)
{
fprintf(stdout, "Word: %s | Amount: %i\n", listWords[i].word, listWords[i].amount);
}
for (int i = 0; i < listSize/2; i++)
{
//free(listWords[i].word);
}
free(listWords);
exit(EXIT_SUCCESS);
}
wordContainer *SetupWordList(int *size, int *lastInit, wordContainer *listIN, bool reallocate)
{
if(!reallocate)
{
listIN = (wordContainer *)malloc((*size) * sizeof(wordContainer));
if (listIN == NULL)
{
fprintf(stderr, "Could not allocate enought memory.");
exit(EXIT_FAILURE);
}
}
else
{
listIN = (wordContainer *)realloc(listIN, (*size) * sizeof(wordContainer));
}
for (int i = (*lastInit); i < (*size); i++)
{
listIN[i].word = (char *)malloc(50*sizeof(char));
listIN[i].word = "empty";
listIN[i].word = "cow";
listIN[i].amount = 0;
}
*lastInit = *size;
*size *= 2;
return listIN;
}
I have honestly no idea what is the problem here, everything I could find online sugested that I am maybe using free() multiple times on the same location or that I have overwriten buffers but I don't see how this is the case here.
for (int i = (*lastInit); i < (*size); i++)
{
listIN[i].word = (char *)malloc(50*sizeof(char));
strcpy(listIN[i].word, "empty");
}
Solved my problem. Did not realise that "listIN[i].word = "empty";" makes me lose my mallocated pointer.
I am trying to scan the input file inside a function, instead of scaning the inputfile in the main function. but seems like it doesn't work this way.
I guess it's the problem of the inputfile pointer, I am not very familiar with using pointers
#include<stdio.h>
typedef struct
{
char firstname[32],lastname[32];
int age;
}mandef;
mandef scaninput(int rows,FILE *inputfile)
{
int i;
mandef man[rows];
for (i = 0; i < rows; i ++)
{
fscanf(inputfile,"%s",&man[i].firstname);
fscanf(inputfile,"%s",&man[i].lastname);
fscanf(inputfile,"%d",&man[i].age);
}
return man;
}
int main ()
{
FILE *inputfile;
inputfile = fopen("input.txt","r");
if (inputfile == NULL)
{
printf("Error: Unable to open input.txt.");
return(1);
}
int i,rows;
char x;
fscanf(inputfile,"%d",&rows);
mandef man[rows];
man = scaninput(rows,inputfile);
return 0;
}
I want the code works the same way as this code
#include<stdio.h>
typedef struct
{
char firstname[32],lastname[32];
int age;
}mandef;
int main ()
{
FILE *inputfile;
inputfile = fopen("input.txt","r");
if (inputfile == NULL)
{
printf("Error: Unable to open input.txt.");
return(1);
}
int i,rows;
fscanf(inputfile,"%d",&rows);
mandef man[rows];
for (i = 0; i < rows; i ++)
{
fscanf(inputfile,"%s",&man[i].firstname);
fscanf(inputfile,"%s",&man[i].lastname);
fscanf(inputfile,"%d",&man[i].age);
}
return 0;
}
input.txt looks like
2
Mike Abc 18
David Abc 17
You return the local variable, it's a bad idea because after the function terminated, this variable may be doesnt existe. So you should use pointer instead:
mandef * man = malloc(sizeof(mandef) * rows);
if(!mandef) {
// handle the error
}
Do not use & for scanning the string, it should be:
fscanf(inputfile,"%s",man[i].firstname);
fscanf(inputfile,"%s",man[i].lastname);
fscanf(inputfile,"%d",&man[i].age);
the test:
#include<stdio.h>
#include <stdlib.h>
typedef struct
{
char firstname[32],lastname[32];
int age;
}mandef;
mandef * scaninput(int rows,FILE *inputfile)
{
int i;
mandef * man = malloc(sizeof(mandef) * rows);
if (!man) {
return NULL;
}
for (i = 0; i < rows; i ++)
{
fscanf(inputfile,"%s",man[i].firstname);
fscanf(inputfile,"%s",man[i].lastname);
fscanf(inputfile,"%d",&man[i].age);
}
return man;
}
int main ()
{
FILE *inputfile;
inputfile = fopen("input.txt","r");
if (inputfile == NULL)
{
printf("Error: Unable to open input.txt.");
return(1);
}
int i,rows;
char x;
fscanf(inputfile,"%d",&rows);
if(rows <= 0)
return -1;
mandef * man;
man = scaninput(rows,inputfile);
for (i = 0; i < rows; i ++)
{
printf("%s\n",man[i].firstname);
printf("%s\n",man[i].lastname);
printf("%d\n",man[i].age);
}
free(man);
return 0;
}
the output:
Mike
Abc
18
David
Abc
17
I would recommend that you figure out pointers and dynamically allocating memory for your array using malloc if that is appropriate. I made some quick changes to your code below, it's far from perfect but it should give you the general idea.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
typedef struct mandef
{
char firstname[32];
char lastname[32];
int age;
} mandef;
mandef *scaninput(int rows,FILE *inputfile)
{
int i;
mandef *man = malloc(sizeof(mandef) * rows);
bzero(man, (sizeof(mandef) * rows));
for (i = 0; i < rows; i++)
{
fscanf(inputfile,"%31s",man[i].firstname);
fscanf(inputfile,"%31s",man[i].lastname);
fscanf(inputfile,"%d",&man[i].age);
}
return man;
}
int main ()
{
FILE *inputfile = fopen("input.txt","r");
if (inputfile == NULL)
{
printf("Error: Unable to open input.txt.");
return(1);
}
int rows=0;
fscanf(inputfile,"%d",&rows);
mandef *man = scaninput(rows,inputfile);
if (rows > 0)
{
printf("man[0].firstname is %s\n", man[0].firstname);
}
return 0;
}
I have to create a program that has an array of costumers (structs that contain name, code and documentation) and functions to insert, remove and list all of them in order of code. I'm not understanding what I should do. Please note that the parameters for insertCostumer, removeCostumer and listCostumer cannot be changed.
Piece of code 01:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#define MAX_REG 10
typedef struct _costumer {
int code;
char name[50];
char documentation[20];
} costumer;
Piece of code 02:
int main(int argc, char** argv) {
costumer *costumers[MAX_REG];
costumer **p_costumer;
p_costumer = &costumers[0];
int count = 0;
memset(costumers, 0, sizeof(costumers));
//Some code to check what to do using a switch
case '1': insertCostumer(p_costumer, &count); getch(); break;
case '2': removeCostumer(p_costumer, &count); getch(); break;
case '3': listCostumers(p_costumer, &count); getch(); break;
//Some code
return (EXIT_SUCCESS);
}
Piece of code 03:
void insertCostumer(costumer **p_costumer, int *count){
char aux[50];
char aux2[20];
if(*count < MAX_REG) {
*p_costumer = (costumer *) malloc(sizeof(costumer));
printf("\nInsert the code: ");
gets(aux);
(*p_costumer)->code = atoi(aux);
printf("Insert the name: ");
gets(aux);
strcpy((*p_costumer)->name, aux);
printf("Insert the documentation: ");
gets(aux2);
strcpy((*p_costumer)->documentation, aux2);
(*count)++;
p_costumer = &*p_costumer[*count];
} else {
printf("List full! Remove a costumer first!\n");
}
}
void removeCostumer(costumer **p_costumer, int *count){
char aux3[50];
int cod;
printf("\nInsert the code of the costumer to be removed: ");
gets(aux3);
cod = atoi(aux3);
for(int i = 0; i < *count; i++) {
if(p_costumer[i]->code == cod) {
strcpy(p_costumer[i]->name, NULL);
p_costumer[i]->code = 0;
strcpy(p_costumer[i]->documentation, NULL);
}
}
}
void listCostumers(costumer **p_costumer, int *count){
for(int i = 0; i < *count; i++) {
printf("Code: %d | Name: %s | Documentation: %s\n", p_costumer[i]->code, p_costumer[i]->name, p_costumer[i]->documentation);
}
}
I don't know what I'm doing wrong; nothing is working, honestly. I was trying to first insert, list and remove to try and make the sorting part later, but I can't even get this part done. When I list, only the last costumer added is listed, for example.
Can someone help me?
Okay, I had to refactor a considerable amount of your code, so I don't have a blow by blow description of the changes.
You'll just have to study it a bit.
Note that even if you're passed a double pointer as an argument, doesn't mean you have to use it as a double in the body of the functions. Note, in particular, what I did for the count (e.g. int count = *p_count; and *p_count = count;)
But, it should be noted that the list is one of pointers to structs and not merely a pointer to an array of structs (i.e. there is an extra level of indirection). This makes things a bit faster.
Note that, bug fixes aside, the key is the "slide" operation in the remove function.
Because we're "sliding" pointers, this is faster/more efficient with the pointer array. Study this [concept] well.
Never use gets--always use fgets
I've deliberately left off comments. This will allow you to add them as you analyze the code. I've found that this can be a powerful technique for understanding a [foreign] code base.
Anyway, here's the code. I've done some rudimentary testing and it seems to work:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//#include <conio.h>
#define MAX_REG 10
char aux[1000];
typedef struct _costumer {
int code;
char name[50];
char documentation[20];
} costumer;
void
lineget(char *buf,size_t buflen)
{
char *cp;
cp = fgets(buf,buflen,stdin);
if (cp != NULL) {
cp = strrchr(buf,'\n');
if (cp != NULL)
*cp = 0;
}
}
void
insertCostumer(costumer **p_costumer, int *p_count)
{
costumer *add;
int count = *p_count;
char aux2[20];
if (count < MAX_REG) {
add = malloc(sizeof(costumer));
printf("\nInsert the code: ");
lineget(aux,sizeof(aux));
add->code = atoi(aux);
printf("Insert the name: ");
lineget(add->name,sizeof(add->name));
printf("Insert the documentation: ");
lineget(add->documentation,sizeof(add->documentation));
p_costumer[count] = add;
++count;
}
else {
printf("List full! Remove a costumer first!\n");
}
*p_count = count;
}
void
removeCostumer(costumer **p_costumer, int *p_count)
{
int count = *p_count;
int cod;
int i;
costumer *cur;
printf("\nInsert the code of the costumer to be removed: ");
fgets(aux,sizeof(aux),stdin);
cod = atoi(aux);
int slide = 0;
for (i = 0; i < count; i++) {
cur = p_costumer[i];
if (cur->code == cod) {
slide = 1;
break;
}
}
if (slide) {
free(cur);
--count;
for (; i < count; ++i)
p_costumer[i] = p_costumer[i + 1];
p_costumer[count] = NULL;
}
*p_count = count;
}
void
listCostumers(costumer **p_costumer, int *p_count)
{
costumer *cur;
int count = *p_count;
for (int i = 0; i < count; ++i, ++cur) {
cur = p_costumer[i];
printf("Code: %d | Name: %s | Documentation: %s\n",
cur->code, cur->name, cur->documentation);
}
}
int
main(int argc, char **argv)
{
costumer *costumers[MAX_REG];
costumer **p_costumer;
char buf[100];
p_costumer = &costumers[0];
int count = 0;
memset(costumers, 0, sizeof(costumers));
setbuf(stdout,NULL);
//Some code to check what to do using a switch
while (1) {
printf("operation to perform (1=insert, 2=remove, 3=print): ");
char *cp = fgets(buf,sizeof(buf),stdin);
if (cp == NULL)
break;
switch (cp[0]) {
case '1':
insertCostumer(p_costumer, &count);
break;
case '2':
removeCostumer(p_costumer, &count);
break;
case '3':
listCostumers(p_costumer, &count);
break;
}
}
return (EXIT_SUCCESS);
}
This function is a part of program which will gain statistics about books (amount of specific letters, words etc.). Thing is that segmentation fault appears when trying to malloc:
*wordArray[arrayIndex] = malloc(sizeof(***wordArray)*(wcslen(newWord)+1));
after reallocing whole array
*wordArray = realloc(*wordArray, (arrayIndex+1)*sizeof(**wordArray));
I know that realloc isn't really efficent but the most important thing at the moment is to understand why it doesn't work at all. Thanks a lot.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>
#include <wctype.h>
#include <wchar.h>
#define X 2
void wordManager(wchar_t ***, int **, wchar_t *);
int main(int argc, char **argv){
setlocale(LC_ALL, "");
wchar_t **wordArray;
int *wordAmount;
wchar_t word[50];
for(int i=0; i<X; i++){
scanf("%ls", word);
wordManager(&wordArray, &wordAmount, word);
}
for(int i=0; i<X; i++){
printf("%ls; %d times\n", wordArray[i], wordAmount[i]);
}
}
void wordManager(wchar_t ***wordArray, int **wordAmount, wchar_t *newWord){
static int isArrayInitialised = 0;
static int isArrayEmpty = 1;
static int arrayIndex = 0;
int wordLocation;
if(!isArrayInitialised){
*wordArray = malloc(sizeof(**wordArray)*1);
if(*wordArray==NULL){
printf("Error mallocing wordArray");
exit(EXIT_FAILURE);
}
*wordAmount = calloc(1, sizeof(*wordAmount));
if(*wordAmount==NULL){
printf("Error callocing wordAmount");
exit(EXIT_FAILURE);
}
isArrayInitialised = 1;
}
if(isArrayEmpty){
*wordArray[0] = malloc(sizeof(***wordArray)*(wcslen(newWord)+1));
wcscpy(*wordArray[0], newWord);
*wordAmount[0] = 1;
isArrayEmpty = 0;
}
else{
//Check if word is already in an array.
wordLocation = 0;
for(; wordLocation<arrayIndex+1; wordLocation++){
if(!wcscmp(*wordArray[wordLocation], newWord)) break;
}
printf("%d\n", wordLocation);
//Word hasn't been found. Then:
if(wordLocation==arrayIndex+1){
arrayIndex++; //Increase arrays' volume.
*wordArray = realloc(*wordArray, (arrayIndex+1)*sizeof(**wordArray));
if(*wordArray==NULL){
printf("Error reallocating wordArray memory.\n Array index: %d", arrayIndex);
exit(EXIT_FAILURE);
}
*wordAmount = realloc(*wordAmount, (arrayIndex+1)*sizeof(**wordAmount));
if(*wordAmount==NULL){
printf("Error reallocating wordAmount memory.\n Array index: %d", arrayIndex);
exit(EXIT_FAILURE);
}
*wordArray[arrayIndex] = malloc(sizeof(***wordArray)*(wcslen(newWord)+1));
wcscpy(*wordArray[arrayIndex], newWord);
*wordAmount[arrayIndex] = 1;
}
//Word has been found in an array.
else{
(*wordAmount[wordLocation])++;
}
}
}
I am having an error with the code we are using, was wondering if someone could help debug. Seems like we are getting a malloc error. Thanks.
void readWords(char norm_word[MAXSIZE], Word ** array) {
int i = 0;
bool found = false;
int result = 0;
Word * current_pointer = malloc (sizeof(Word*));//creates a temporary variable for each pointer in the array
for (i=0; i<word_counter; i++) {
current_pointer = *(array+i); //accesses the current pointer
result = strcmp(norm_word, (current_pointer -> word)); //compares the string to each stored string
if (result == 0) {
found = true;
(current_pointer->freq)++;
break;
}
}
if(!found) {
if(pointer_counter == word_counter) {
array = realloc(array, sizeof(array)*2);
pointer_counter*=2;
}
Word * new_pointer = (Word*) malloc (sizeof(Word*));
strcpy(new_pointer -> word, norm_word);
*(array + (pointer_counter - 1)) = new_pointer;
word_counter++;
}
;
}
All pointers have the same size on your system. So a sizeof always returns the same size for any pointer. You want to allocate for the structure, so you need to use sizeof on the name without the star. malloc will return the pointer to that block of memory afterwards.
Here is a short implementation:
#include <iostream>
#include <string>
typedef struct
{
int num;
int numnum;
}numbers;
int main(int argc, char ** argv)
{
numbers* n = (numbers*)malloc(sizeof(numbers));
n->num = 1;
n->numnum = 2;
free(n);
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define MAXSIZE 64
typedef struct word {
char word[MAXSIZE];
int freq;
} Word;
int word_counter = 0;
size_t pointer_counter = 16;//Number of pointers that ensure
void readWords(char norm_word[MAXSIZE], Word ** array) {
int i = 0;
bool found = false;
Word *current_pointer = *array;
for (i=0; i<word_counter; i++) {
if(strcmp(norm_word, current_pointer->word) == 0){
found = true;
current_pointer->freq++;
break;
}
++current_pointer;
}
if(!found) {
if(pointer_counter == word_counter) {
pointer_counter *= 2;
*array = realloc(*array, sizeof(Word)*pointer_counter);
}
Word *new_pointer = *array + word_counter;
new_pointer->freq = 1;
strcpy(new_pointer->word, norm_word);
++word_counter;
}
}
int main(void){
Word *vocabulary = calloc(pointer_counter, sizeof(Word));
char norm_word[MAXSIZE];
while(1==scanf("%s", norm_word)){
readWords(norm_word, &vocabulary);
}
{
int i;
for(i = 0; i < word_counter; ++i){
printf("%s(%d)\n", vocabulary[i].word, vocabulary[i].freq);
}
}
free(vocabulary);
return 0;
}