How to read a large file in C on Linux
Reading a large file in C on Linux involves opening the file, reading its contents in chunks, and processing each chunk as needed. Here's a simple example using the standard C library functions:
#include <stdio.h>
#include <stdlib.h>
#define BUFFER_SIZE 4096 // Adjust the buffer size as needed
int main() {
FILE *file;
char buffer[BUFFER_SIZE];
size_t bytesRead;
// Open the file for reading
file = fopen("your_large_file.txt", "rb");
if (file == NULL) {
perror("Error opening file");
return 1;
}
// Read and process the file in chunks
while ((bytesRead = fread(buffer, 1, sizeof(buffer), file)) > 0) {
// Process the buffer (you can replace or extend this part)
// For example, print the content of the buffer:
fwrite(buffer, 1, bytesRead, stdout);
}
// Close the file
fclose(file);
return 0;
}Explanation:
- The fopen function is used to open the file for reading in binary mode ("rb").
- A buffer (buffer) of a specified size is used to read the file in chunks. You can adjust the BUFFER_SIZE to suit your needs.
- The fread function reads a chunk of data from the file into the buffer.
- Process the buffer as needed. In this example, it simply prints the content to the standard output using fwrite.
- The loop continues until fread returns 0, indicating the end of the file or an error.