I am making a program that reads a file and counts how many words the .txt have. The program is working just fine, the problem is that if the txt have a break line it stops reading, so i have to put all my text in one line. As far as i know the problem is in fgets, that stops reading when it reaches EOF or a new line. My question is: How do i reads my text even with new lines ? Do i have to use fread() ? If so, would i do? Below is the part of the code where i read the .txt and put in an array.
char linha[10000];
int grandezaStrings = 100000;
int i = 0;
int contadorString = 0;
// This line reads the file.
fgets (linha, grandezaStrings,myFile);
// Used for special characters
setlocale (LC_ALL,"PORTUGUESE");
// Dynamic array to hold words
char ** strings = (char **)malloc(grandezaStrings * sizeof (char*));
char * pch;
for (i=0;i<grandezaStrings; i++){
strings[i] = (char *)malloc(100+1);
}
// Transfer all the words to my array.
i = 0;
pch = strtok(linha, " ,.!?:;()\n");
while (pch != NULL){
strlwr(pch);
strings[i] = pch;
contadorString++;
pch = strtok (NULL, " ,.!?:;()\n");
i++;
}
Thanks a lot!
fgets reads up to next new line. It is by design. You could loop (while (fgets(...) != NULL)) or if you want to load everything in memory in one single read, you can just use a fread :
// This line reads the whole file.
i = fread (linha, 1, grandezaStrings,myFile);
if (i < 0) { // test read Ok
perror("Lettura");
return 1;
}
linha[i] = '\0'; // add the terminating null
Use fgets() to get line by line from the file and perform your operation on the line.
while(fgets (linha, sizeof(linha),myFile) != NULL)
{
// perform the action on the line.
}
Use sizeof(linha) as the number of characters to be read.
Related
I am pulling words from a file but I need to check if the file follows a specific format.
"The source file format is one word per line. If a line does not follow that format, then it should be skipped" My code is not checking for this and I have no idea how I would even begin its just pulling one line no matter what and strtok it word by word. please help me. Im a beginner.
I tried using an if statement to check for new lines and I couldn't seem to get it to work maybe I just had it in the wrong place.
const char *get_word_from_file(FILE *file)
{
char words[MAX_WORDS][MAX_WORD_LEN]; // inner one is the outer most view
char buf[MAX_LINE_LEN];
size_t idx = 0;
while (fgets(buf, sizeof(buf), file))
{
char *word = strtok(buf, " ?.,\n-\"");
while (word)
{
strncpy(words[idx], word, sizeof(words[idx])); // Destination, src, size of destination to prevent overflow
word = strtok(NULL, " ?.,\n-\"");
++idx;
}
}
fclose(file);
srandom(time(NULL)); // seeding with current time
// generating a random number and picking a word from words array
int random_number = random() % idx;
char *random_word = words[random_number];
// Allocating memory for the word
char *verified_random_word = allocate_word_memory(random_word);
return verified_random_word;
}
What is the most accurate way to read strings from the keyboard in C, when the string contains spaces in between words? When I use scanf for that purpose then it doesn't read a string with spaces.The second option is to use gets but it is supposed to be harmful(I also want to know why?).Another thing is that I don't want to use any file handling concept like fgets.
These are 2 ways to read strings containing spaces that don't use gets or fgets
You can use getline (POSIX 2008 may not exist in your system) that conveniently manages allocation of the buffer with adequate size to capture the whole line.
char *line = NULL;
size_t bufsize = 0;
size_t n_read; // number of characters read including delimiter
while ((n_read = getline(&line, &bufsize, stdin)) > 1 && line != NULL) {
// do something with line
}
If you absolutely want scanf, in this example it reads to the end of line unless the line has more than the specified number of chars minus 1 for the delimiter. In the later case the line is truncated and you'll get the remaining chars in the next scanf invocation.
char line[1024];
while (scanf("%1023[^\n]\n", line) == 1) {
// do something with line
}
I should also point out that when you read strings from the keyboard with scanf for example, you are actually reading from a file with file pointer stdin. So you can't really avoid "any file handling concept"
#user3623265,
Please find a sample program which Uses fgets to read string from standard input.
Please refer some sample C documents as to how fgets can be used to get strings from a keyboard and what is the purpose of stdin.
#include <stdio.h>
#include <string.h>
int main(void)
{
char str[80];
int i;
printf("Enter a string: ");
fgets(str, sizeof(str), stdin);
i = strlen(str) - 1;
if (str[i] == '\n')
str[i] = '\0';
printf("This is your string: %s", str);
return 0;
}
There is a third option, you can read the raw data from stdin with the read() call:
#include <unistd.h>
int main(void) {
char buf[1024];
ssize_t n_bytes_read;
n_bytes_read = read(STDIN_FILENO, buf, sizeof(buf) - 1);
if (n_bytes_read < 0) {
// error occured
}
buf[n_bytes_read] = '\0'; // terminte string
printf("\'%s\'", buf);
return 0;
}
Please not that every input is copied raw to buf including the trailing return. That is, if you enter Hello World you will get
'Hello World
'
as output. Try online.
If you insist on not having a FILE * in scope, use getchar().
char buff[1024];
int ch;
int i = 0;
while( (ch = getchar()) != '\n' )
if(i < 1023)
buff[i++] = ch;
buff[i] = 0;
/* now move string into a smaller buffer */
Generally however it's accepted that stdout and stdin and FILE * are available. Your requirement is a bit odd and, since you are obviously not an advanced C programmer who has an unusual need to suppress the FILE * symbol, I suspect your understanding of C IO is shaky.
I am trying to read a textfile like this
1234567890 1234
9876543210 22
into a List struct in my program. I read in the files via fgets() and then use strtok to seperate the numbers, put them into variables and then finally into the List. However, I find that in doing this and printing the resulting strings, strtok always takes the final string in the final line to be NULL, thus resulting in a segmentation fault.
fgets(fileOutput,400,filePointer); //Read in a line from the file
inputPlate = strtok(fileOutput," "); // Take the first token, store into inputPlate
while(fileOutput != NULL)
{
string = strtok(NULL," ");
mileage = atoi(string); //Convert from string to integer and store into mileage
car = initializeCar(mileage,dateNULL,inputPlate);
avail->next = addList(avail->next,car,0);
fgets(fileOutput,400,filePointer);
inputPlate = strtok(fileOutput," ");
}
How do I resolve this?
Reading a text file line by line with fgets() is good.
Not checking the return value of fgets() is weak. This caused OP's code to process beyond the last line.
// Weak code
// fgets(fileOutput,400,filePointer); //Read in a line from the file
// ...
// while(fileOutput != NULL)
// {
Better to check the result of fgets() to determine when input is complete:
#define LINE_SIZE 400
...
while (fgets(fileOutput, LINE_SIZE, filePointer) != NULL)
{
Then process the string. A simple way to assess parsing success to is to append " %n" to a sscanf() format to record the offset of the scan.
char inputPlate[LINE_SIZE];
int mileage;
int n = -1;
sscanf(fileOutput, "%s%d %n", inputPlate, &mileage, &n);
// Was `n` not changed? Did scanning stop before the string end?
if (n < 0 || fileOutput[n] != '\0') {
Handle_Bad_input();
break;
} else {
car = initializeCar(mileage, dateNULL, inputPlate);
avail->next = addList(avail->next,car,0);
}
}
You could write a simpler parser with fscanf():
FILE *filePointer;
... // code not shown for opening the file, initalizing the list...
char inputPlate[32];
int mileage;
while (fscanf(filePointer, "%31s%d", inputPlate, &mileage) == 2) {
car = initializeCar(mileage, dateNULL, inputPlate);
avail->next = addList(avail->next, car, 0);
}
So I am opening a file that contains cards data for a card game I am designing for my assignment, basically each line contains 104 characters and each line is equal to a deck of card.
I'm using a char **** because of
number of decks
num of players (4)
num of cards (13)
card is represented like 9H, 3D means nine of hearts and three of diamonds, so it uses 2 characters.
I want to use fgets() to read multiple lines but I'm not sure if this works...
for loop is just the way how the deckfile is set, I just want to know if the fgets will go to the next line when it hits \n...
di->cards = (char ****)malloc(sizeof(char***) * di->numDecks);
for (i = 0; i < di->numDecks; i++) {
di->cards[i] = (char ***)malloc(sizeof(char**) * 4);
for (j = 0; j < 4, j++) {
di->cards[i][j] = (char **)malloc(sizeof(char*) * 13);
for (k = 0, k < 13, k++) {
di->cards[i][j][k] = (char *)malloc(sizeof(char) * 3);
}
}
}
for (i = 0; i < di->numDecks, i++) {
for (j = 0; j < 13, j++) {
for (k = 0; k < 4; k++) {
while ((fgets(cards[i][k][j], 3, di->deckFile)) != NULL);
}
}
}
fgets() is often called in a loop, such as this:
FILE *fp;
char buf[260];// or char *buf, then use malloc - make index size appropriate length for anticipated line len.
fp = fopen("C:\\somedir\\card.txt", "r");
while(fgets(buf, sizeof(buf), fp)) //where sizeof(buf) is the length of
//line you anticipate reading in.
{
//do something with buf here;
//The input of fgets will be NULL as soon
//as its input fp has been fully read, then exit the loop
}
fclose(fp);
Your statement while((fgets(cards[i][k][j], 3, di->deckFile)) != NULL);
has a couple of issues, one is the ; at the end. It will just loop on this one line, and not give you a chance to do anything with the line that is read before it reads the next one. Also, 3 is probably not the length of line you want to read, is it? 3 is the buffer size that will hold your card data, but the line you read from the file will be longer.
So, in addition to these points, consider the other ideas in the comments, and make changes as indicated.
[EDIT] modified to read a file with "AS3D4C...(52 cards)" 4 lines
It will fill in enough spaces for 4 decks of cards. You can use this to
see how to read in the data. strtok (used before) works only when there
are delimiters, which if you can, I would recommend using instead of
long strings. Hope this helps.
(Note, I used no [mc]alloc()'s in this example.
#include <ansi_c.h>
#define FILENAME "C:\\dev\\play\\cards.txt"
int main()
{
int i, j;
FILE *fp;
char buf[260];// or char *buf, then use malloc - make index size appropriate length for anticipated line len.
char *cardTok;
char cards[208][3]; //4 players, 4 decks, each card is 3 bytes (eg. [A|S|\0], they all need a null termination)
memset(cards, 0, 208*3);
fp = fopen(FILENAME, "r");
j = 0;
while(fgets(buf, sizeof(buf), fp)) //where buf len is initialized at 260
//and well over the anticipated 104/line, including \n etc.
{ //note, fgets() will read up to n-1 characters and place a \0 at the end
//but will stop reading sooner if it sees end of line.
for(i=0;i<52;i++) //i is card number
{
cards[i+j][0] = buf[2*i+0];
cards[i+j][1] = buf[2*i+1];
cards[i+j][2] = 0;
}
j+=52;
}
fclose(fp);
}
My text file looked like this:
9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD3D4SQhKD1H9H3D4SQhKDKD1H9H3D4SQhKD
6C9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD3D4SQhKD1H9H3D4SQhKDKD1H9H3D4SQh
2D9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD3D4SQhKD1H9H3D4SQhKDKD1H9H3D4SQh
3S9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H9H3D4SQhKD1H1H9H3D4SQhKD1H9H3D4SQhKD3D4SQhKD1H9H3D4SQhKDKD1H9H3D4S
#include <stdio.h>
char *fgets(char *s, int size, FILE *stream);
fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline.
be careful with this : If a newline is read, it is stored into the buffer. A terminating null byte ('\0') is stored after the last character in the buffer.
When you want to compare line , before you need to remove \n before null byte.
If you want to read single line.
char line[100]; // here you can use char *line=malloc(100);
fgets(line,sizeof line,file_stream);
printf("%s\n",line);
if you want to read multiple lines
char lines[20][100]; // here you can use char **lines=malloc(100);
i=0;
//if you use **lines allocate size for all lines with the loop or else you can allocate size inside loop and then read.
while((fgets(lines[i],SIZE_ALLOCATED_FOR_LINE,file_stream)!=NULL) && (i<20))
{
printf("%s\n",line[i++]);
}
The documentation says,
char *fgets( char *str, int count, FILE *stream );
char *fgets( char *restrict str, int count, FILE *restrict stream );
Reads at most count - 1 characters from the given file stream and
stores them in str. The produced character string is always
NULL-terminated. Parsing stops if end-of-file occurs or a newline
character is found, in which case str will contain that newline
character.
Also,
The return value is NULL on failure.
If the failure has been caused by EOF condition, additionally sets the eof indicator (see feof()) on stdin. If the failure has been caused by some other error, sets the error indicator (see ferror()) on stdin.
Also check for feof to ensure NULL was obtained due to EOF
If you want to take the fgets input and input all of it into an array of arrays or string array how could you do that. I have tried different things but get seg faults
I have an input file I need to extract words from. The words can only contain letters and numbers so anything else will be treated as a delimiter. I tried fscanf,fgets+sscanf and strtok but nothing seems to work.
while(!feof(file))
{
fscanf(file,"%s",string);
printf("%s\n",string);
}
Above one clearly doesn't work because it doesn't use any delimiters so I replaced the line with this:
fscanf(file,"%[A-z]",string);
It reads the first word fine but the file pointer keeps rewinding so it reads the first word over and over.
So I used fgets to read the first line and use sscanf:
sscanf(line,"%[A-z]%n,word,len);
line+=len;
This one doesn't work either because whatever I try I can't move the pointer to the right place. I tried strtok but I can't find how to set delimitters
while(p != NULL) {
printf("%s\n", p);
p = strtok(NULL, " ");
This one obviously take blank character as a delimitter but I have literally 100s of delimitters.
Am I missing something here becasue extracting words from a file seemed a simple concept at first but nothing I try really works?
Consider building a minimal lexer. When in state word it would remain in it as long as it sees letters and numbers. It would switch to state delimiter when encountering something else. Then it could do an exact opposite in the state delimiter.
Here's an example of a simple state machine which might be helpful. For the sake of brevity it works only with digits. echo "2341,452(42 555" | ./main will print each number in a separate line. It's not a lexer but the idea of switching between states is quite similar.
#include <stdio.h>
#include <string.h>
int main() {
static const int WORD = 1, DELIM = 2, BUFLEN = 1024;
int state = WORD, ptr = 0;
char buffer[BUFLEN], *digits = "1234567890";
while ((c = getchar()) != EOF) {
if (strchr(digits, c)) {
if (WORD == state) {
buffer[ptr++] = c;
} else {
buffer[0] = c;
ptr = 1;
}
state = WORD;
} else {
if (WORD == state) {
buffer[ptr] = '\0';
printf("%s\n", buffer);
}
state = DELIM;
}
}
return 0;
}
If the number of states increases you can consider replacing if statements checking the current state with switch blocks. The performance can be increased by replacing getchar with reading a whole block of the input to a temporary buffer and iterating through it.
In case of having to deal with a more complex input file format you can use lexical analysers generators such as flex. They can do the job of defining state transitions and other parts of lexer generation for you.
Several points:
First of all, do not use feof(file) as your loop condition; feof won't return true until after you attempt to read past the end of the file, so your loop will execute once too often.
Second, you mentioned this:
fscanf(file,"%[A-z]",string);
It reads the first word fine but the file pointer keeps rewinding so it reads the first word over and over.
That's not quite what's happening; if the next character in the stream doesn't match the format specifier, scanf returns without having read anything, and string is unmodified.
Here's a simple, if inelegant, method: it reads one character at a time from the input file, checks to see if it's either an alpha or a digit, and if it is, adds it to a string.
#include <stdio.h>
#include <ctype.h>
int get_next_word(FILE *file, char *word, size_t wordSize)
{
size_t i = 0;
int c;
/**
* Skip over any non-alphanumeric characters
*/
while ((c = fgetc(file)) != EOF && !isalnum(c))
; // empty loop
if (c != EOF)
word[i++] = c;
/**
* Read up to the next non-alphanumeric character and
* store it to word
*/
while ((c = fgetc(file)) != EOF && i < (wordSize - 1) && isalnum(c))
{
word[i++] = c;
}
word[i] = 0;
return c != EOF;
}
int main(void)
{
char word[SIZE]; // where SIZE is large enough to handle expected inputs
FILE *file;
...
while (get_next_word(file, word, sizeof word))
// do something with word
...
}
I would use:
FILE *file;
char string[200];
while(fscanf(file, "%*[^A-Za-z]"), fscanf(file, "%199[a-zA-Z]", string) > 0) {
/* do something with string... */
}
This skips over non-letters and then reads a string of up to 199 letters. The only oddness is that if you have any 'words' that are longer than 199 letters they'll be split up into multiple words, but you need the limit to avoid a buffer overflow...
What are your delimiters? The second argument to strtok should be a string containing your delimiters, and the first should be a pointer to your string the first time round then NULL afterwards:
char * p = strtok(line, ","); // assuming a , delimiter
printf("%s\n", p);
while(p)
{
p = strtok(NULL, ",");
printf("%S\n", p);
}