I'm new here and new to C.
I want to print an array out of a file with fopen but it does not seem to work.
My empty array is char matrix[25][25], and now I am trying to open a text file and print it into the array. The txt file is named Matrix1.txt and consists out of 625 characters that are either '*' or ' '.
What I am trying to do now is:
//openfile(), LÄNGE=Lenght=25, BREITE=Height=25, datei=file, matrix=array
int dateiöffnen(char matrix[][LÄNGE], char* datei){
FILE *fp;
char cell;
fp = fopen(datei, "r");
if (fp == NULL){
printf("Fehler!\n"); //Fehler=Error
}
else{
for (int y = 0; y < BREITE; y++){
for (int x = 0; x > LÄNGE; x++){
fscanf(fp, "%c", &cell);
matrix[x][y] = cell;
}
}
fclose(fp);
}
}
So later I try to print the array and play the Game of life with that printed array (it's in a switch):
case 1:
dateiöffnen(matrix, "Matrix1.txt");
play(matrix);
print(matrix);
but for some reason it prints a blank array and if I try to run the openfile() in the main function like this
int main(int argc, char *argv[]) {
char matrix[BREITE][LÄNGE];
int x, y;
//srand(time(NULL));
dateiöffnen(matrix, "Matrix1.txt");
}
it prints an array like this:
So I am very confused and would be glad and thankful if someone could give me a hint what's going on.
There is probably a typo in the inner for loop:
for (int x = 0; x > LÄNGE; x++){
should be:
for (int x = 0; x < LÄNGE; x++){
Related
I am trying to read a text file with 100 numbers like 1 2 45 55 100 text file here (all on a single line) and then put them in a 10x10 array (2D array).
736.2 731.6 829.8 875.8 568.3 292.2 231.1 868.9 66.7 811.9 292.0 967.6 419.3 578.1 322.5 471.7 980.0 378.8 784.1 116.8 900.4 355.3 645.7 603.6 409.1 652.1 144.1 590.6 953.1 954.0 502.0 689.3 685.6 331.9 565.1 253.9 624.1 796.2 122.8 690.7 608.0 414.8 658.3 27.3 992.9 980.8 499.0 972.8 359.7 283.1 89.7 260.1 638.4 735.4 863.6 47.5 387.5 7.7 638.1 340.6 961.7 140.1 29.8 647.3 471.9 594.9 901.2 96.0 391.1 24.0 786.7 999.1 438.7 445.0 26.4 431.6 425.9 525.4 404.4 785.6 808.5 494.1 45.7 447.0 229.5 909.3 494.4 617.0 917.0 132.5 957.5 878.8 272.6 987.4 526.1 744.5 582.3 427.3 840.5 973.3
Here is my code:
#include <stdio.h>
#define NR 10
#define NC 10
int main(void) {
int numbers[9][9];
int i = 0;
int count;
int j = 0;
FILE *file;
file = fopen("numbers.txt", "r");
for (count = 1; count < 101; count++) {
fscanf(file, "%d", &numbers[i][j]);
j++;
if ((count != 1) && (count % 10 == 0)) {
i++;
j = 0;
}
}
fclose(file);
int p = 0;
int q = 0;
for (p = 0; p < NR; p++) {
for (q = 0; q < NC; q++) {
printf("%d", numbers[p][q]);
}
printf("\n");
}
return 0;
}
As SparKot noted in a comment, to read a 10x10 matrix, you need to define the matrix with 10x10 elements:
int numbers[10][10];
That has to be one of the weirder ways of reading a 10x10 matrix that I've ever seen. Why not go for a simple approach of nested loops. Since the data contains floating-point numbers, you need to read them as double (or perhaps float) values.
for (int i = 0; i < 10; i++)
{
for (int j = 0; j < 10; j++)
{
double double_val;
if (fscanf(file, "%lf", &double_val) != 1)
{
fprintf(stderr, "failed to read matrix[i][j]\n", i, j);
exit(EXIT_FAILURE);
}
numbers[i][j] = double_val;
}
}
The mess with double_val works around the data containing floating point numbers and your original code trying to read integers. You'll get one valid value; thereafter, fscanf() will return 0 because the . is not a part of a valid integer. This highlights the importance of checking the return value from fscanf() and its relatives.
Frankly, you should be using double numbers[10][10]; for the data from the file. Then you could read directly into the array:
if (fscanf("%lf", &numbers[i][j]) != 1)
But you'd need to check (and probably change) all the rest of the code too.
There are multiple issues in your code:
the matrix is too small, make it numbers[NR][NC].
you do not check for fopen failure: you will have undefined behavior if the file numbers.txt is not in the current directory or cannot be open for reading.
you read the file contents as integers, but the file contains floating point numbers with a . decimal separator: the second and subsequent fscanf() will get stuck on the . and keep returning 0 without modifying the destination number, leaving the matrix mostly uninitialized. Make the matrix double numbers[NR][NC], read the numbers with %lf and test for conversion failure.
the counting method in the reading loop is weird. Just use 2 nested for loops with proper counter and tests.
printing the matrix contents, you should output at least a space between numbers so the output is readable.
Here is a modified version:
#include <errno.h>
#include <stdio.h>
#include <string.h>
#define NR 10
#define NC 10
int main() {
double numbers[NR][NC];
FILE *file;
file = fopen("numbers.txt", "r");
if (file == NULL) {
fprintf(stderr, "cannot open numbers.txt: %s\n", strerror(errno));
return 1;
}
for (int i = 0; i < NR; i++) {
for (int j = 0; j < NC; j++) {
if (fscanf(file, "%lf", &numbers[i][j]) != 1) {
fprintf(stderr, "error reading number at row %d, col %d\n",
i + 1, j + 1);
fclose(file);
return 1;
}
}
}
fclose(file);
for (int p = 0; p < NR; p++) {
for (int q = 0; q < NC; q++) {
printf(" %5g", numbers[p][q]);
}
printf("\n");
}
return 0;
}
Clear all a common condition that causes programs to crash; they are often associated with a file named core.
code is showing segmentation fault.
Here, the array pointer name[i] is not not working and I can't figure out how to change the pointer or the array to make it work. There was no compiler error/warning but the console terminal showed a negative return value and printf() was not working.
Also, the output file was created but it was empty: nothing was written into it.
I guess there's some problem with the fscanf() action of taking string input from file.
#include<stdio.h>
#include<math.h>
int main()
{
FILE *fr, *fw;
fr = fopen("data.txt", "r");
float wt[10], ht[10], bmi[10];
char *name[5];
for(int i = 0; i < 5; i++)
{
fscanf(fr, "%s\t%f\t%f", &name[i], &wt[i], &ht[i]);
bmi[i] = wt[i] / pow(ht[i], 2);
}
printf("%s", name[2]);
fw = fopen("bmi.txt", "w");
for(int j = 0; j < 5; j++)
{
fprintf(fw, "%s\t%f\n", name[j], bmi[j]);
}
fclose(fr);
fclose(fw);
return 0;
}
You should not assume that the file size is 5. You should dynamically allocate memory to the name variable like so:
int length;
fseek(filename, 0, SEEK_END);
length = ftell(filename);
name = malloc(length);
fread(name, 1, length, filename);
below I have posted my code. When I compile I receive no errors, and only one warning about variables I haven't used yet. the code works all the way to the line in code where it starts to print. I have tested all the sections and I believe that one is at fault. please let me know what I am doing wrong so I can fix it.
#include <stdio.h>
#include <string.h>
#define NUM_LINES 37
#define LINE_LENGTH 60
void select_sort_str(char list[NUM_LINES][LINE_LENGTH], int n);
int alpha_first(char list[NUM_LINES][LINE_LENGTH], int min_sub, int max_sub);
int main (void){
//store each line in an array of strings
FILE *inp;
FILE *outp;
char hurr[NUM_LINES][LINE_LENGTH];
;
inp = fopen("hurricanes.csv","r");
outp = fopen("out.txt","w");
//read in lines from file
for (int i = 0; i<NUM_LINES; i++){
fgets(hurr[i], LINE_LENGTH, inp);
}
inp = fopen("hurricanes.cvs","r");
//printf("%s", hurr[0]);
//define function
select_sort_str(hurr, NUM_LINES);
return(0);
}
int
alpha_first(char list[NUM_LINES][LINE_LENGTH], // input - array of pointers to strings
int min_sub, // input - min and max subscripts of
int max_sub) // portion of list to consider
{
int first, i;
first = min_sub;
for (i = min_sub + 1; i <= max_sub; ++i) {
if (strcmp(list[i], list[first]) < 0) {
first = i;
}
}
return (first);
}
/*
* Orders the pointers in an array list so they access strings in
* alphabetical order
* Pre: first n elements of list reference string of uniform case;
* n >= 0
*/
void
select_sort_str(char list[NUM_LINES][LINE_LENGTH], // input/output - array of pointers being
// ordered to acces strings alphabetically
int n) // input - number of elements to sort
{
int fill, // index of element to contain next string in order
index_of_min; // index of next string in order
char *temp;
char temp1[NUM_LINES][LINE_LENGTH];
for (fill = 0; fill < n - 1; ++fill) {
index_of_min = alpha_first(list, fill, n - 1);
if (index_of_min != fill) {
temp = list[index_of_min];
list[index_of_min][LINE_LENGTH] = list[fill][LINE_LENGTH];
strncpy(temp1[index_of_min], list[index_of_min], LINE_LENGTH);
temp1[fill][LINE_LENGTH] = *temp;
}
}
char *name;
char *cat = 0;
char *date;
for (int i = 0; i<NUM_LINES; i++){
name = strtok(NULL, ",");
cat = strtok(NULL, "h");
date = strtok(NULL, " ");
printf("%s %s %s\n", name, cat, date);
}
// for( int i =0; i<NUM_LINES; i++){
// printf("%s", list[i]);
// }
}
The only first parameter you ever pass to strtok is NULL. You never actually give it anything to parse. Did you perhaps mean strtok(temp1[i], ",");?
Also, why no error checking? It's much easier to find bugs in code with error checking.
I have 32 bits as a text file in Sender.txt like
00100100101110001111111100000001
I want to store each individual number as an integer in the array. I have tried the following code but not working.
#include <stdio.h>
#include<stdlib.h>
void main()
{
FILE *myfile;
myfile = fopen("Sender.txt" , "r");
char data[32];
int i,con, data1[32];
for(i=0;i<32;i++)
{
fscanf(myfile, "%1s", &data[i]);
}
for(i=0;i<32;i++)
{
con = atoi(data[i]);
data1[i]=con;
}
for(i=0;i<32;i++)
{
printf("%d \n", &data1[i]);
}
}
Still without fully understanding the purpose of your endeavor, I suggest to rewrite the first two loops:
for(i = 0; i < 32; i++)
{
int next = fgetc(myfile);
data1[i] = (next == '0') : 0 ? 1;
}
This code assumes that the file has 32 1's or 0's, all on the same line, and nothing else.
This could be further compressed, possibly at the expense of clarity:
for(i = 0; i < 32; i++)
{
data1[i] = fgetc(myfile) - '0';
}
Why don't you use fgetc ? This function reads only one Charakter and returns it.
Your code should then look like this:This one got errors see EDIT
FILE *file;
char c[32];
for(int i = 0; i < 32; i++){
if((c[i] = fgetc(file)) == NULL)
//then Error
}
fclose(file);
EDIT: As rightly pointed out by "alk" (what a name mate xD) The if clause makes no sense at all. It was to early in the morning i apologize. The right code should of course look like this:
FILE *file;
int data[32]; //The Question was to store the Data in an int not char like i did...
for(int i = 0; i < 32; i++)
data[i] = fgetc(file) - '0';
fclose(file);
Best regards
I am new to C and have been trying to do this for a while now.
I need to read the integer values from a text file that has :
G = 10
P = 5
Gayle: 1,2,3,4
Price: 4,3,5,6.6
Need to pick out the Gayle and Price values and store them in 2 seperate arrays and store the G and P values in 2 separate variables.
So far I have done :
FILE* file = fopen(abc.txt, "r");
//for gayle values
int g_array[100];
int i=0;
int gayle_val;
while(fscanf("%d", &gayle_val)==1)
{
g_array[i]=gayle_val;
}
//for price values
int p_array[100];
int i=0;
int price_val;
while(fscanf("%d", &price_val)==1)
{
p_array[i]=price_val;
}
//for G and P values
How do I combine the searches for the 4 lines such that the read is done line by line and values stored accordingly ?
Thank you so much in advance !
This has been answered before and I'm pretty sure it was suggested to you as the question was typed:
I am not going to give you a code sample but instead am going to advise you on what could be done to get the contents of the file to be inserted in a single array rather than one.
Try to create a 2D array instead and assigning the values to it rather than having multiple arrays and use a FOR loop to do so.
simple E.G.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void){
int gayle_val, g_array[100], g_count, p_count;
float price_val, p_array[100];
int i;
char line_buff[128], *p;
FILE *file = fopen("abc.txt", "r");
while(NULL!=fgets(line_buff, sizeof(line_buff), file)){
if(strncmp("G = ", line_buff, 4) == 0){//simple match
gayle_val = atoi(line_buff + 4);
} else if(strncmp("P = ", line_buff, 4) == 0){
price_val = atof(line_buff + 4);
} else if(strncmp("Gayle: ", line_buff, 7) == 0){
g_count = 0;
for(p = line_buff + 7;NULL!=(p=strtok(p, ","));p=NULL){
g_array[g_count++] = atoi(p);
}
} else if(strncmp("Price: ", line_buff, 7) == 0){
p_count = 0;
for(p = line_buff + 7;NULL!=(p=strtok(p, ","));p=NULL){
p_array[p_count++] = atof(p);
}
}
}
fclose(file);
//check print
printf("gayle_val: %d\n", gayle_val);
printf("gayle: ");
for(i = 0;i<g_count;++i)
printf("%d ", g_array[i]);
printf("\n");
printf("price_val: %g\n", price_val);
printf("price: ");
for(i = 0;i<p_count;++i)
printf("%g ", p_array[i]);
printf("\n");
return 0;
}