erstellen einer temporaeren Datei und auslesen einer Zeile daraus
-
Hallo,
Ich wollte mit temporaeren Dateien etwas herumexpirementieren und habe hier die problematischen Funktionen aus meinem Programm zu einem Demo zusammengefasst.Das Demo sollte einfach einen mehrzeiligen Text in ein Tempfile schreiben, dann eine Zeile daraus auslesen und das Tempfile wieder schliessen - es sollte damit dann doch auch wieder geloescht sein (oder?).
Das Programm kompiliert durch, es laeuft auch, nur kann eine entsprechende Zeile nicht ausgelesen werden. Wo liegt der Fehler?
#include <stdlib.h> #include <stdio.h> #include <string.h> int create_tmp(FILE** fp, char szTmp[L_tmpnam]) { if(szTmp == NULL){ szTmp = tmpnam(szTmp); if( (*fp = fopen(szTmp, "rw")) == NULL){ fprintf(stderr, "fo::create_fmp(FILE*, char[]) - Failed!\n"); return -1; } }else{ if((*fp = tmpfile()) == NULL){ fprintf(stderr, "fo::create_tmp(FILE*, char[]) - Failed!\n"); return -1; } } return 0; }; int close_tmp(FILE** fp) { if(fp == NULL) return -1; rewind(*fp); fclose(*fp); *fp = NULL; return 0; }; int write_linewise(FILE* fp, char* content, const unsigned long int CONTENT_SIZE) { if(fp == NULL) return -1; if(content == NULL) return -1; char bufLine[BUFSIZ]; int idxLine = 0; int idxContent = 0; char *pData = &content[0]; strcpy(bufLine, ""); while((idxLine < BUFSIZ) && (idxContent < CONTENT_SIZE) && ((bufLine[idxLine] = *(pData++)) != '\0')){ if (idxLine >= BUFSIZ){ fprintf(stderr, "fo::write_linewise(FILE*, char*, const unsigned long) - Failed!\n"); return -1; } if( ((idxLine == CONTENT_SIZE-2) && (bufLine[idxLine] != '\n')) || (*(pData+1) == '\0' )){ bufLine[idxLine+1] = '\0'; fputs(bufLine, fp); // write line break; }else if(bufLine[idxLine] == '\n'){ fputs(bufLine, fp); // write line idxLine = 0; }else{ ++idxLine; } ++idxContent; } fputs("\n\0", fp); // tailing linefeed + linebreak return 0; }; int read_nth_line(FILE* fp, char* line, const unsigned long int LINE_SIZE, const unsigned long int LINE_NUMBER) { if(fp == NULL) return -1; char temp[LINE_SIZE]; int cnt=0; for(cnt = 0; cnt < LINE_NUMBER - 1; ++cnt) if(fgets(temp, LINE_SIZE, fp) == NULL) return -1; if(fgets(temp, LINE_SIZE, fp) == NULL) return -1; strcat(line, temp); return 0; }; int main() { // init FILE* fp = NULL; fp = malloc(sizeof(FILE)); char text1[] = "Jack and Jill went up the hill to fetch a pail of water\n"; char text2[] = "Jack fell down and broke his crown\nAnd Jill came tumbling after.\n"; char text3[] = "Up got Jack, and home did trot\nAs fast as he could caper\n"; char text4[] = "He went to bed and bound his head\nWith vinegar and brown paper.\n"; unsigned long int text1_size = sizeof(text1); unsigned long int text2_size = sizeof(text2); unsigned long int text3_size = sizeof(text3); unsigned long int text4_size = sizeof(text4); unsigned long int content_size = 2 * BUFSIZ; char *content = malloc(content_size*sizeof(char)); strcpy(content,""); char szTmp[] = "tmp.txt"; // create FILE* printf("%i - Create temp file pointer (read/write): %s\n", create_tmp(&fp, szTmp), szTmp); // write the lines printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text1, text1_size), szTmp); printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text2, text2_size), szTmp); printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text3, text3_size), szTmp); printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text4, text4_size), szTmp); // read the nth line printf("%i - Read the %i. line (first line index: 1) of \'\%s\'\n", read_nth_line(fp, content, content_size, 2), 2, szTmp); // FIXME printf("content:\n\'%s\'\n", content); strcpy(content,""); // close the tmp file printf("%i - And close the \'%s\' file again\n", close_tmp(&fp), szTmp); printf("Done.\n\n"); //*/ return EXIT_SUCCESS; };
-
Siehe meine Antwort von
http://www.c-plusplus.net/forum/viewtopic-var-t-is-199369-and-highlight-is-rewind.html
-
Hallo, hatte leider keine Zeit eher zu antworten - ich benutze nun
rewind() - leider geht es immer noch nicht, der ausgelesene String
besteht nur aus einem \n. Wo liegt mein Fehler?
Hier die ueberarbeitete Version:
// tempfile.c #include <stdlib.h> #include <stdio.h> #include <string.h> int create_tmp(FILE** fp, char szTmp[L_tmpnam]) { if(szTmp == NULL){ szTmp = tmpnam(szTmp); if( (*fp = fopen(szTmp, "rw")) == NULL){ fprintf(stderr, "fo::create_fmp(FILE*, char[]) - Failed!\n"); return -1; } }else{ if((*fp = tmpfile()) == NULL){ fprintf(stderr, "fo::create_tmp(FILE*, char[]) - Failed!\n"); return -1; } } return 0; }; int close_tmp(FILE** fp) { if(fp == NULL) return -1; fclose(*fp); *fp = NULL; return 0; }; int write_linewise(FILE* fp, char* content, const unsigned long int CONTENT_SIZE) { if(fp == NULL) return -1; if(content == NULL) return -1; char bufLine[BUFSIZ]; int idxLine = 0; int idxContent = 0; char *pData = &content[0]; strcpy(bufLine, ""); rewind(fp); // reset filestream while((idxLine < BUFSIZ) && (idxContent < CONTENT_SIZE) && ((bufLine[idxLine] = *(pData++)) != '\0')){ if (idxLine >= BUFSIZ){ fprintf(stderr, "fo::write_linewise(FILE*, char*, const unsigned long) - Failed!\n"); return -1; } if( ((idxLine == CONTENT_SIZE-2) && (bufLine[idxLine] != '\n')) || (*(pData+1) == '\0' )){ bufLine[idxLine+1] = '\0'; fputs(bufLine, fp); // write line break; }else if(bufLine[idxLine] == '\n'){ fputs(bufLine, fp); // write line idxLine = 0; }else{ ++idxLine; } ++idxContent; } fputs("\n\0", fp); // tailing linefeed + linebreak return 0; }; int read_nth_line(FILE* fp, char* line, const unsigned long int LINE_SIZE, const unsigned long int LINE_NUMBER) { #ifdef DEBUG printf("\tfo::read_nth_line(*fp, *line, LINE_SIZE, LINE_NUMBER)\n"); printf("\t%i - fp == NULL\n", (fp == NULL)); printf("\t%i - &*fp\n", &*fp); printf("\t%i - line == NULL\n", (line == NULL)); printf("\t%i - LINE_SIZE\n", LINE_SIZE); printf("\t%i - LINE_NUMBER\n", LINE_NUMBER); #endif if(fp == NULL) return -1; rewind(fp); // reset filestream char temp[LINE_SIZE]; int cnt=0; for(cnt = 0; cnt < LINE_NUMBER - 1; ++cnt) if(fgets(temp, LINE_SIZE, fp) == NULL) return -1; if(fgets(temp, LINE_SIZE, fp) == NULL) return -1; strcat(line, temp); return 0; }; int main() { // init FILE* fp = NULL; fp = malloc(sizeof(FILE)); char text1[] = "Jack and Jill went up the hill to fetch a pail of water\n"; char text2[] = "Jack fell down and broke his crown\nAnd Jill came tumbling after.\n"; char text3[] = "Up got Jack, and home did trot\nAs fast as he could caper\n"; char text4[] = "He went to bed and bound his head\nWith vinegar and brown paper.\n"; unsigned long int text1_size = sizeof(text1); unsigned long int text2_size = sizeof(text2); unsigned long int text3_size = sizeof(text3); unsigned long int text4_size = sizeof(text4); unsigned long int content_size = 2 * BUFSIZ; char *content = malloc(content_size*sizeof(char)); strcpy(content,""); char szTmp[] = "tmp.txt"; // create FILE* printf("%i - Create temp file pointer (read/write): %s\n", create_tmp(&fp, szTmp), szTmp); // write the lines printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text1, text1_size), szTmp); printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text2, text2_size), szTmp); printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text3, text3_size), szTmp); printf("%i - Append some text to the \'%s\' (linewise)\n", write_linewise(fp, text4, text4_size), szTmp); // read the nth line printf("%i - Read the %i. line (first line index: 1) of \'\%s\'\n", read_nth_line(fp, content, content_size, 2), 2, szTmp); // FIXME printf("content:\n\'%s\'\n", content); strcpy(content,""); // close the tmp file printf("%i - And close the \'%s\' file again\n", close_tmp(&fp), szTmp); printf("Done.\n\n"); //*/ return EXIT_SUCCESS; };