Name

gzgets — Reads a string from a compressed file.

Library

Libz.lib

Synopsis

#include <zlib.h>

char * gzgets (gzFile file, char * buf, int len);

Return Value

On success, gzgets() shall return a pointer to buf. Otherwise, gzgets() shall return Z_NULL. Applications may examine the cause using gzerror().

Detailed Description

The gzgets() function shall attempt to read data from the compressed file stream file, uncompressing it into buf until either len-1 bytes have been inserted into buf, or until a newline character has been uncompressed into buf. A null byte shall be appended to the uncompressed data. The file shall have been opened in for reading (see gzopen() and gzdopen()).

Examples

#include <stdio.h>
#include <zlib.h>    
void Gzgets( )
{ 
    Byte *compr, *uncompr;
    uLong comprLen = 20*sizeof(int);     
    uLong uncomprLen = comprLen;
    compr    = (Byte*)calloc((uInt)comprLen, 1);    
    uncompr  = (Byte*)calloc((uInt)uncomprLen, 1);
    compress(compr, &comprLen, (const Bytef*)hello, len);
        
    file = gzopen(fname, "rb");
    strcpy((char*)uncompr, "garbage");

    gzread(file, uncompr, (unsigned)uncomprLen) != len    
    gzseek(file, -8L, SEEK_CUR);
    gzgets(file, (char*)uncompr, (int)uncomprLen);    
    int outlen = strlen((char*)uncompr);
    printf("length of the output is %d",outlen);
    gzclose(file);    
	
    free(compr);
    free(uncompr);       
}

Output

length of the output is 7.

Errors

On error, gzgets() shall return Z_NULL. The following conditions shall always be treated as an error:

file is NULL, or does not refer to a file open for reading;

buf is NULL;

len is less than or equal to zero.

Feedback

For additional information or queries on this page send feedback