Reading a text file in C - c

Question

I am reading a text file and trying to display its contents on the console. Here is my code:
#include "stdafx.h"
#include <stdio.h>
#include <string.h>
#include <fstream>
int main()
{
FILE* fp=NULL;
char buff[100];
fp=fopen("myfile.txt","r");
if(fp==NULL)
{
printf("Couldn't Open the File!!!\n");
}
fseek(fp, 0, SEEK_END);
size_t file_size = ftell(fp);
fread(buff,file_size,1,fp);
printf("Data Read [%s]",buff);
fclose(fp);
return 0;
}
but only redundant data is being displayed on the console; could someone please point out my mistake?

Answer 1

You forgot to reset the file pointer to start after doing this.
fseek(fp, 0, SEEK_END);
Do this after finding size (file_size).
rewind (fp);

Answer 2

You need to seek back to the start of the file before reading:
int main()
{
FILE* fp=NULL;
char buff[100];
fp=fopen("myfile.txt","r");
if(fp==NULL)
{
printf("Couldn't Open the File!!!\n");
exit(1); // <<< handle fopen failure
}
fseek(fp, 0, SEEK_END);
size_t file_size = ftell(fp);
fseek(fp, 0, SEEK_SET); // <<< seek to start of file
fread(buff,file_size,1,fp);
printf("Data Read [%s]",buff);
fclose(fp);
return 0;
}

Answer 3

Try it....
#include <stdio.h>
#include <stdlib.h>
void handle_line(char *line) {
printf("%s", line);
}
int main(int argc, char *argv[]) {
int size = 1024, pos;
int c;
char *buffer = (char *)malloc(size);
FILE *f = fopen("myfile.txt", "r");
if(f) {
do { // read all lines in file
pos = 0;
do{ // read one line
c = fgetc(f);
if(c != EOF) buffer[pos++] = (char)c;
if(pos >= size - 1) { // increase buffer length - leave room for 0
size *=2;
buffer = (char*)realloc(buffer, size);
}
}while(c != EOF && c != '\n');
buffer[pos] = 0;
// line is now in buffer
handle_line(buffer);
} while(c != EOF);
fclose(f);
}
free(buffer);
return 0;
}

Answer 4

#include "stdafx.h"
#include <stdio.h>
#include <string.h>
#include <fstream>
int main()
{
FILE* fp=NULL;
char *buff; //change array to pointer
fp=fopen("myfile.txt","r");
if(fp==NULL)
{
printf("Couldn't Open the File!!!\n");
}
fseek(fp, 0, SEEK_END);
size_t file_size = ftell(fp);
buff = malloc(file_size); //allocating memory needed for reading file data
fseek(fp,0,SEEK_SET); //changing fp to point start of file data
fread(buff,file_size,1,fp);
printf("Data Read [%s]",buff);
fclose(fp);
return 0;
}

Answer 5

having a buffer of 100 bytes to read a file is not a better idea as since the file size may be more than 100 bytes.
A better file io can be done by doing a fgets on the file, if its not a type of metadata that you wanted to read using the fread.
fgets in a while loop can be used to check whether its reached EOF or a feof call can be used to check the EOF.
a sample code listing of fgets can be like this:
while (fgets(buf, len, fp)) {
printf("%s", buf);
}
or a sample that is used with fgets can be like this:
while (fread(buf, len, 1, fp) >= 0) {
printf("%s\n", buf);
}