97 lines
3.0 KiB
C
97 lines
3.0 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include "file_utils.h"
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/************************************************************************************
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* @author Jacob McCloughan
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* @version 3/03/2017
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* @see file_utils.h
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*
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* Implementation for file_utils.h. Contains functions
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* for reading from a file and putting it into a selected array
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* and for writing the array backwards into a selected file.
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*
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* This post taught me everything I now know about files in C:
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* http://stackoverflow.com/questions/22697407/reading-text-file-into-char-array
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*************************************************************************************/
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/*
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* Reads the .txt file passed as a parameter into the array (buffer)
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* pointed to as a parameter.
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*
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* @param filename, the name of the .txt file being read from.
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* @param buffer, a pointer to the array that will have the data read in.
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* @return 0 if the operation failed and the number of bytes if it succeeded.
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*/
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int read_file(char* filename, char **buffer) {
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// Variables. The stat struct is from Professor Woodring.
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FILE *fil;
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struct stat st;
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stat(filename, &st);
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int size = st.st_size;
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// Opens up the file for extracting the data. If statement is for error-checking.
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fil = fopen(filename, "r");
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if (!fil) {
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fprintf(stderr, "Unable to read file.");
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return 0;
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}
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// Creates the space for our array. If statement is for error-checking.
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*buffer = malloc((size) * sizeof(char));
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if (!*buffer) {
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fprintf(stderr, "Unable to allocate memory.");
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fclose(fil);
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return 0;
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}
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/* Reads the data into our array. If statement is for error-checking, but it also contains the
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command that reads in the data. */
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if (fread(*buffer, size, 1, fil) != 1) {
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fprintf(stderr, "Error copying file to memory.");
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fclose(fil);
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return 0;
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}
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// Closes the file and returns the size of the array.
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fclose(fil);
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return size;
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}
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/*
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* Writes to the filename passed as a parameter from the array (buffer)
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* passed as a parameter. The size of the array must be specified.
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*
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* @param filename, the name of the .txt file being written to.
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* @param buffer, the array that the data is being written from.
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* @param size, the size of the array. If read in properly by the read_file
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* function, this should have been returned.
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* @return 0 if the operation failed and 1 if it succeeded.
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*/
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int write_file(char* filename, char *buffer, int size) {
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// File being operated on.
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FILE *fil;
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// Opens up the file for printing the data. If statement is for error-checking.
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fil = fopen(filename, "w");
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if (!fil) {
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fprintf(stderr, "Unable to write to that file.");
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fclose(fil);
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return 0;
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}
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/* Iterates through the buffer passed and prints it backwards to a text file.
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If statement is for error-checking, but it also contains the command that writes the data. */
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for (int i = 0; i < size; i++) {
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if (fprintf(fil, "%c", buffer[i]) != 1) {
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fprintf(stderr, "Error when writing to file.");
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fclose(fil);
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return 0;
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}
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}
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// Closes the file and returns 1.
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fclose(fil);
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return 1;
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}
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