I am trying to read from a .txt file that has some numbers in lines.
It looks like that.
example.txt
123
456
789
555
I open this as a binary file for reading wanted to read this file line by line so i know that in every line theres 4 characters (3 numbers and 1 new line character '\n').
I am doing this:
FILE * fp;
int page_size=4;
size_t read=0;
char * buffer = (char *)malloc((page_size+1)*sizeof(char));
fp = fopen("example.txt", "rb"); //open the file for binary input
//loop through the file reading a page at a time
do {
read = fread(buffer,sizeof(char),page_size, fp); //issue the read call
if(feof(fp)!=0)
read=0;
if (read > 0) //if return value is > 0
{
if (read < page_size) //if fewer bytes than requested were returned...
{
//fill the remainder of the buffer with zeroes
memset(buffer + read, 0, page_size - read);
}
buffer[page_size]='\0';
printf("|%s|\n",buffer);
}
}
while(read == page_size); //end when a read returned fewer items
fclose(fp); //close the file
In printf is expected this result then
|123
|
|456
|
|789
|
|555
|
but the actual result i am taking is:
|123
|
456|
|
78|
|9
6|
|66
|
so it looks like that after the first 2 fread it reads only 2 numbers and something goes completely wrong with the new line character.
So what is wrong with fread here?
Answer
You can use the following to read the file line by line.
FILE * fp;
char * line = NULL;
size_t len = 0;
ssize_t read;
while ((read = getline(&line, &len, fp)) != -1) {
printf("Line length: %zd :\n", read);
printf("Line text: %s", line);
}