CODEWITHSUNDEEP
cmemorycharallocationrealloc
Fragender99
Fragender99

Reputation: 3

C dynamic allocation with realloc of a char**

I'm new here and don't speak very well english. I've a question concerning my code (in C).

What the code should do: There exists a file named "g.txt", that should be opened. Then it reads it line by line and copies each line in a buffer (zpuffer[200]), after that the content of the buffer should be copied with strcpy to **Dfile. **Dfile points to a char*, its space was first allocated with malloc. If **Dfile hasn't enough space for saving, the code executes realloc, that shoud make more free space.

The first time realloc have been called, I actually got more space! But the second time, it didn't work; the OS, Ubuntu, says (in German): "Bus-Zugriffsfehler (Speicherabzug geschrieben)". English: "Bus access error (written dump)"

Here is my code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define OBJS 10 //new Lines a one time for **Dfile

int main(void){
FILE *datei;
datei=fopen("g.txt", "r");
if (datei == NULL){
    fprintf(stderr, "\nFEHLER\n");
    return 1;
}

char zpuffer[200]; //buffer
char **Dfile; //save content of g.txt line by line, every line has its own index

int zeilen = 0; //the actual amount of lines
int speicher = 0; //total indices in **Dfile    
Dfile = (char**)malloc(sizeof(char**)*(speicher + OBJS));
speicher += OBJS;   

while (fgets(zpuffer, 199, datei) != NULL){ 
    if (speicher <= zeilen){//speicher <= zeilen --> allocate memory
        Dfile = (char**)realloc(*Dfile, sizeof(char**)*(speicher + OBJS)); //!!ERROR!! but just the second time!!
        if (Dfile == NULL){
            fprintf(stderr, "\nFEHLER Alloc\n");
            return 1;
        }           
        speicher += OBJS;
    }

    Dfile[zeilen]=malloc(strlen(zpuffer)+1);
    strcpy(Dfile[zeilen++], zpuffer);       
    printf("%s", Dfile[zeilen - 1]);    
}
return 0;
}

May someone help me, please??

Upvotes: 0

Views: 544

Answers (1)

PineForestRanch
PineForestRanch

Reputation: 473

You pass *Dfile to realloc().

Did you meant to pass Dfile instead?

Upvotes: 2

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