CODEWITHSUNDEEP
c
Chris
Chris

Reputation: 179

Read() is reading junk data before reading actual data

Im having an issue using the read() function in C.

I have a file lets say fileX which has the contents:

Data to be outputted

However when I open the file and use read on it I get garbage data using the code below

ssize_t reader = 0;
ssize_t writer = 0;
char buffer[256];
reader = read(myFile, buffer, 256);
//check if reader is -1, if so then exit(1)
writer = write(1, buffer, 256);
//check if writer is -1, if so then exit(1)

The read function seems to run twice. Once with a bunch of garbage data then followed by the actual data in the file. Any idea how to remedy this?

Upvotes: 0

Views: 142

Answers (1)

bobra
bobra

Reputation: 625

Are you sure that your buffer is filled with '\0', finished with '\0' ? And you call write with 256 - in 3rd arg

#include <fcntl.h>

int main() {
    const int max_size = 256;    
    char buffer[max_size] = {};
    int my_input    = open("input", O_TEXT, S_IREAD);

    ssize_t reader;
    ssize_t writer;
    reader =  read(my_input, buffer, max_size);
    if(reader != -1)
        writer = write(1, buffer, reader);

    return 0;
}

Upvotes: 1

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