#include using namespace std; #include #include // fopen #include // exit #include //strlen /* * The C constant EOF is a status flag indicating end of file has been reached. * The ASCII character EOF is Ctrl-Z (character 26) * and will truncate file ops in text (vs binary) mode * * Run this to see the "gotcha" (at ^ Whoops). * Live Q&A link in comments * */ FILE* fn; const char *FILENAME = "file_with_embedded_EOF_character.txt"; void createTextOnlySample() { fn = fopen(FILENAME, "w"); if(fn == NULL) { printf("Something went wrong; unable to create test file.\n"); exit(1); // see ya } const char* outLinePart1 = "SOME "; const char* outLinePart2 = "TEXT"; fprintf(fn, outLinePart1); // 5 char fprintf(fn, "%c", 26); // 1 char fprintf(fn, outLinePart2); // 4 char printf("==>[%s^Z%s]<==\n\nOutput string length: %d\n", outLinePart1, outLinePart2, strlen(outLinePart1) +1+ strlen(outLinePart2)); fclose(fn); // cwrites an ASCII EOF? } #include void displayFileSize() { struct stat filestat; stat(FILENAME, &filestat); printf("File size from:\n stat, SEEK(txt), SEEK(bin), Windows:\n %d, ", filestat.st_size); fn = fopen(FILENAME, "r"); fseek(fn, 0L, SEEK_END); printf("%d, ", ftell(fn)); fclose(fn); fn = fopen(FILENAME, "rb"); fseek(fn, 0L, SEEK_END); printf("%d, ", ftell(fn)); fclose(fn); // no error checking HANDLE file = CreateFile(TEXT(FILENAME), GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); DWORD fsz = GetFileSize(file, NULL); printf("%d\n", fsz); CloseHandle(file); } const int BUFSIZE = 12; // arbitrary..just larger void displayFileReads() { // BINARY READ ======================= char bufferB[BUFSIZE]; fn = fopen(FILENAME, "rb"); printf("\nBuffer BIN read: null term = 0\n"); // should only read once while(fgets(bufferB, sizeof bufferB, fn) != NULL) { printf(" >> Read a BINARY block\n"); } printf(" >> feof fired? [%s]\n", feof(fn)>0 ? "Yes" : "No"); for(int i=0; i> Read a TEXT block\n"); } printf(" >> feof fired? [%s]\n", feof(fn)>0 ? "Yes" : "No"); for(int i=0; i void displayDirectory() { struct dirent *de; DIR *dirp = opendir("."); if(dirp) { while((de = readdir(dirp)) != NULL) { if(de->d_type == 0) // normal file printf("%s\n", de->d_name); } closedir(dirp); } } */

Files gotcha (EOF flag vs ASCII 26)