I wrote a short code that should copy the content of a file into an initialized array of strings and then print that array. I get no errors/warnings but still the program doesn't print anything when i run it. The code is the following:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
const int dim = 30;
int main() {
char* arr[dim];
int i = 0;
FILE* fp;
fp = fopen("test.txt", "r+");
if(fp == NULL) {
printf("\nError, breaking...");
return 0;
}
while(i <= dim) {
arr[i] = (char *)malloc(dim*sizeof(char *));
++i;
}
i = 0;
while(fscanf(fp, "%s", arr[i]) != EOF) {
printf("%s: added\n", arr[i]);
++i;
}
}
The file contains a series of words separated only by whitespaces and newline characters.
correct followings and see if it helps
1) initialise i to 0 ie. i=0;
2)
while(i < dim) { } // it should be < as array start with 0
Related
Currently I am making a project that uses char arrays that have null elements. I want to be able to get the length of the array, in the sense of the number of elements that aren't null. This seemed reasonably trivial and I made this function:
int getWordLen(char word[]) {
int count = 0;
for (int i = 0; i < 512; i++) {
if (word[i] != '\0') {
count++;
}
}
printf("%d ", count);
return count;
}
However, every char array returns a length of 188. Any help would be appreciated.
This is the function I was calling it from:
void redact(Words * redactWords, char fileName[]) {
FILE * file = fopen(fileName, "r");
FILE * outputFile = fopen("outputFile.txt", "w+");
char word[512];
int i = 0;
char c;
while (c != EOF) {
c = getc(file);
if ((c > 96) && (c < 123)) {
word[i] = c;
i++;
continue;
}
else if ((c > 64) && (c < 91)) {
word[i] = c + 32;
i++;
continue;
}
i = 0;
if (isWordRedactWord(redactWords, word)) {
//write stars to file
char starStr[512];
for (int i = 0; i < getWordLen(word); i++) {
starStr[i] = '*';
}
fputs(starStr, outputFile);
}
else {
//write word to file
fputs(word, outputFile);
}
strcpy(word, emptyWord(word));
}
fclose(file);
fclose(outputFile);
}
In the initial while, I would only use while(!EOF).
Also, I believe you are using a lot more resources than necessary with the implementation of that for inside the while:
char starStr[512];
for (int i = 0; i < getWordLen(word); i++) {
starStr[i] = '*';
I suggest you to put it outside the while loop and see what happens.
If it is always giving you 188 of lenght, it is counting something that's constant, and may be related to that outer loop.
Hope you can solve it!
I have created a program that reads a series of strings from a .txt file and after compiling a new .txt file is created where the strings should be in alphabetical order.The problem is that I can't write more than 10 words, the compiler just stops/crashes, WHY? Does it depend by the type of compiler? I am currently using Code-Bloks.How can I optimize the code to run more smoothly?
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void arrange(int n, char *x[])
{
char *temp;
int i,str;
for(str = 0; str < n-1; ++str)
{
for(i = str+1; i < n; ++i)
{
if(strcmp(x[str],x[i]) > 0)
{
temp = x[str];
x[str] = x[i];
x[i] = temp;
}
}
}
return;
}
int number_of_lines = 0;
void countOfLinesFromFile(char *filename){
FILE* myfile = fopen(filename, "r");
int ch;
do
{
ch = fgetc(myfile);
if(ch == '\n')
number_of_lines++;
}
while (ch != EOF);
if(ch != '\n' && number_of_lines != 0)
number_of_lines++;
fclose(myfile);
return number_of_lines;
}
int main()
{
int i , ts=0;
char *x[10];
char *fileName = "WORDS.txt";
countOfLinesFromFile(fileName);
printf("%d",number_of_lines);
FILE * fp;
fp = fopen ("WORDS.txt", "r");
for(i = 0; i < number_of_lines; i++)
{
x[i] = (char*) malloc (1200*sizeof(char));
fscanf(fp, "%s", x[i]);
}
FILE *fPointer;
fPointer=fopen("Alphabetical.txt","w+");
arrange(i,x);
for(i = 0; i < number_of_lines; i++)
{
fprintf(fPointer,"%s\n",x[i]);
}
fclose(fPointer);
fclose(fp);
return 0;
}
char *x[10];
The buffer size is too small
These two lines define how much information you can store
char *x[10]; // 10 strings
x[i] = (char*) malloc (1200*sizeof(char)); // 1200 characters each
As it is written now, you can only hold a maximum of 10 strings with each string being no longer than 1200 characters.
The crash is caused when number_of_lines >= 11 in the following for loop:
for(i = 0; i < number_of_lines; i++)
{
x[i] = (char*) malloc (1200*sizeof(char));
fscanf(fp, "%s", x[i]);
}
When i is 11 you write to x[11] which is past the end of x.
I have a .csv file that reads like:
SKU,Plant,Qty
40000,ca56,1245
40000,ca81,12553.3
40000,ca82,125.3
45000,ca62,0
45000,ca71,3
45000,ca78,54.9
Note: This is my example but in reality this has about 500,000 rows and 3 columns.
I am trying to convert these entries into a 2D array so that I can then manipulate the data. You'll notice that in my example I just set a small 10x10 matrix A to try and get this example to work before moving on to the real thing.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
const char *getfield(char *line, int num);
int main() {
FILE *stream = fopen("input/input.csv", "r");
char line[1000000];
int A[10][10];
int i, j = 0;
//Zero matrix
for (i = 0; i < 10; i++) {
for (j = 0; j < 10; j++) {
A[i][j] = 0;
}
}
for (i = 0; fgets(line, 1000000, stream); i++) {
while (j < 10) {
char *tmp = strdup(line);
A[i][j] = getfield(tmp, j);
free(tmp);
j++;
}
}
//print matrix
for (i = 0; i < 10; i++) {
for (j = 0; j < 10; j++) {
printf("%s\t", A[i][j]);
}
printf("\n");
}
}
const char *getfield(char *line, int num) {
const char *tok;
for (tok = strtok(line, ",");
tok && *tok;
tok = strtok(NULL, ",\n"))
{
if (!--num)
return tok;
}
return 0;
}
It prints only "null" errors, and it is my belief that I am making a mistake related to pointers on this line: A[i][j] = getfield(tmp, j). I'm just not really sure how to fix that.
This is work that is based almost entirely on this question: Read .CSV file in C . Any help in adapting this would be very much appreciated as it's been a couple years since I last touched C or external files.
It looks like commenters have already helped you find a few errors in your code. However, the problems are pretty entrenched. One of the biggest issues is that you're using strings. Strings are, of course, char arrays; that means that there's already a dimension in use.
It would probably be better to just use a struct like this:
struct csvTable
{
char sku[10];
char plant[10];
char qty[10];
};
That will also allow you to set your columns to the right data types (it looks like SKU could be an int, but I don't know the context).
Here's an example of that implementation. I apologize for the mess, it's adapted on the fly from something I was already working on.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// Based on your estimate
// You could make this adaptive or dynamic
#define rowNum 500000
struct csvTable
{
char sku[10];
char plant[10];
char qty[10];
};
// Declare table
struct csvTable table[rowNum];
int main()
{
// Load file
FILE* fp = fopen("demo.csv", "r");
if (fp == NULL)
{
printf("Couldn't open file\n");
return 0;
}
for (int counter = 0; counter < rowNum; counter++)
{
char entry[100];
fgets(entry, 100, fp);
char *sku = strtok(entry, ",");
char *plant = strtok(NULL, ",");
char *qty = strtok(NULL, ",");
if (sku != NULL && plant != NULL && qty != NULL)
{
strcpy(table[counter].sku, sku);
strcpy(table[counter].plant, plant);
strcpy(table[counter].qty, qty);
}
else
{
strcpy(table[counter].sku, "\0");
strcpy(table[counter].plant, "\0");
strcpy(table[counter].qty, "\0");
}
}
// Prove that the process worked
for (int printCounter = 0; printCounter < rowNum; printCounter++)
{
printf("Row %d: column 1 = %s, column 2 = %s, column 3 = %s\n",
printCounter + 1, table[printCounter].sku,
table[printCounter].plant, table[printCounter].qty);
}
// Wait for keypress to exit
getchar();
}
There are multiple problems in your code:
In the second loop, you do not stop reading the file after 10 lines, so you would try and store elements beyond the end of the A array.
You do not reset j to 0 at the start of the while (j < 10) loop. j happens to have the value 10 at the end of the initialization loop, so you effectively do not store anything into the matrix.
The matrix A should be a 2D array of char *, not int, or potentially an array of structures.
Here is a simpler version with an allocated array of structures:
#include <stdio.h>
#include <stdlib.h>
typedef struct item_t {
char SKU[20];
char Plant[20];
char Qty[20];
};
int main(void) {
FILE *stream = fopen("input/input.csv", "r");
char line[200];
int size = 0, len = 0, i, c;
item_t *A = NULL;
if (stream) {
while (fgets(line, sizeof(line), stream)) {
if (len == size) {
size = size ? size * 2 : 1000;
A = realloc(A, sizeof(*A) * size);
if (A == NULL) {
fprintf(stderr, "out of memory for %d items\n", size);
return 1;
}
}
if (sscanf(line, "%19[^,\n],%19[^,\n],%19[^,\n]%c",
A[len].SKU, A[len].Plant, A[len].Qty, &c) != 4
|| c != '\n') {
fprintf(stderr, "invalid format: %s\n, line);
} else {
len++;
}
}
fclose(stream);
//print matrix
for (i = 0; i < len; i++) {
printf("%s,%s,%s\n", A[i].SKU, A[i].Plant, A[i].Qty);
}
free(A);
}
return 0;
}
Im tryin to read a ascii-file consisting of 2 columns of and a variable nr of rows. Reading is done by processor 0 and then the data is distributed using MPI_Bcast(...). I had to create a 1-dim buffer array which contains the data and is sent to all other procs because I haven't found a way to directly broadcast the 2-dim. data.
There's something wrong with the allocation of the array arr. When I try to print the data, the first 3 rows are printed and then I get a segmentation fault. Most likely there are several mistakes.
I really tried to make the example as simple as possible.
my code:
//global variables
...
double **testarray;
int dim;
...
int main(int argc, char **argv){
...
...
read_file("test.txt",&testarray,&dim);
}
int read_file(char* infilename,double ***arr,int *rowsout)
{
FILE* infile;
int i,j,ch,number_of_lines=0;
int rows=0;
//first count lines
if(myid==0) //myid is processor id
{
infile = fopen(infilename, "r");
do
{
ch = fgetc(infile);
if(ch == '\n')
number_of_lines++;
} while (ch != EOF);
if(ch != '\n' && number_of_lines != 0)
number_of_lines++;
//close file
fclose(infile);
rows=number_of_lines-1;
*rowsout=rows;
}
// every proc should know about length of file in order
//to be able to allocate memory
MPI_Bcast(rowsout,1,MPI_INT,0,MPI_COMM_WORLD);
//allocate memory
double *buf; //1D-buffer for 2D-array
MPI_Alloc_mem((*rowsout)*2*sizeof(double), MPI_INFO_NULL, &buf);
MPI_Alloc_mem((*rowsout)*sizeof(double*), MPI_INFO_NULL,arr);
for (i = 0; i < (*rowsout); i++) {
MPI_Alloc_mem(2*sizeof(double),MPI_INFO_NULL,&arr[i]);
}
// Now read file on proc 0
if(myid==0)
{
infile=fopen(infilename,"r");
for(i=0;i<rows;i++)
{
for(j=0;j<2;j++)
{
fscanf(infile,"%lf",arr[i][j]);
printf("arr[%d][%d]:%e\n",i,j,(*arr)[i][j]);
}
}
fclose(infile);
}
return 0;
//dont go further, error occurs before loop finishs
MPI_Bcast(buf,(rows)*2,MPI_DOUBLE,0,MPI_COMM_WORLD);
//now reconstruct array from buffer
for(i=0;i<(*rowsout);i++)
{
for(j=0;j<2;j++)
{
*arr[i][j]=buf[i*2+j];
}
}
MPI_Free_mem(buf);
return 0;
}
You have some issues with your arr as you guessed. Here is a fixed version of your code (minus the MPI stuff):
#include <stdio.h>
#include <stdlib.h>
void read_file(char *filename, double ***arr, int *rowsout);
int main(void)
{
double **testarray;
int dim;
read_file("test.txt", &testarray, &dim);
return 0;
}
void read_file(char *filename, double ***arr, int *rowsout)
{
FILE *infile;
int i, j, ch;
infile = fopen(filename, "r");
do
{
ch = fgetc(infile);
if (ch == '\n')
++*rowsout;
} while (ch != EOF);
rewind(infile);
*arr = malloc(sizeof **arr * *rowsout);
for (i = 0; i < *rowsout; ++i)
(*arr)[i] = malloc(sizeof ***arr * 2);
for (i = 0; i < *rowsout; ++i)
{
for (j = 0; j < 2; ++j)
{
fscanf(infile, "%lf", &(*arr)[i][j]);
printf("(*arr)[%d][%d]: %e\n", i, j, (*arr)[i][j]);
}
}
fclose(infile);
for (i = 0; i < *rowsout; ++i)
free((*arr)[i]);
free(*arr);
}
Example input: test.txt
0.01 0.02
0.3 0.4
5.0 6.0
Example output:
(*arr)[0][0]: 1.000000e-02
(*arr)[0][1]: 2.000000e-02
(*arr)[1][0]: 3.000000e-01
(*arr)[1][1]: 4.000000e-01
(*arr)[2][0]: 5.000000e+00
(*arr)[2][1]: 6.000000e+00
I believe the mistake comes with your fscanf() line. fscanf() wants a double * when you are using "%lf", but you are instead passing arr[i][j] and there's two things wrong with that: since arr is actually a pointer to your 2-D array, you will need to deference it first ((*arr)), and second, since it needs the address of the double, you will need to use &: &(*arr)[i][j].
If I have an options file along the lines of this:
size = 4
data = 1100010100110010
And I have a 2d size * size array that I want to populate the values in data into, what's the best way of doing it?
To clarify, for the example I have I'd want an array like this:
int[4][4] array = {{1,1,0,0}, {0,1,0,1}, {0,0,1,1}, {0,0,1,0}}. (Not real code but you get the idea).
Size can be really be any number though.
I'm thinking I'd have to read in the size, maloc an array and then maybe read in a string full of data then loop through each char in the data, cast it to an int and stick it in the appropriate index? But I really have no idea how to go about it, have been searching for a while with no luck.
Any help would be cool! :)
int process_file(int **array, char const *file_name)
{
int size = 0;
FILE *file = fopen(file_name, "rt");
if(fp == null)
return -1;//can't open file
char line[1024]; //1024 just for example
if(fgets(line, 1024, file) != 0)
{
if(strncmp(line, "size = ", 7) != 0)
{
fcloes(file);
return -2; //incorrect format
}
size = atoi(line + 7);
array = new int * [size];
for(int i = 0; i < size; ++i)
array[i] = new int [size];
}
else
{
fclose(file);
return -2;//incorrect format
}
if(fgets(line, 1024, file) != 0)
{
if(strncmp(line, "data = ", 7) != 0)
{
fcloes(file);
for(int i = 0; i < size; ++i)
delete [] array[i];
delete [] array;
return -2; //incorrect format
}
for(int i = 7; line[i] != '\n' || line[i] != '\0'; ++i)
array[(i - 7) / size][(i - 7) % size] = line[i] - '0';
}
else
{
fclose(file);
for(int i = 0; i < size; ++i)
delete [] array[i];
delete [] array;
return -2; //incorrect format
}
return 0;
}
Don't forget delete array before program ends;
Loops.
FILE *fp = fopen("waaa.txt", "r");
if(fp == null) { /* bleh */ return; }
int j = 0;
while(char ch = fgetc(fp)) {
for(int i = 0; i < 4; ++i) {
array[j][i] = ch;
}
++j;
}
I am not sure with the fgetc() syntax.. Just check on it. It reads one character at a time.