# getline

## NAME



           getline, getdelim - delimited string input
    


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## SYNOPSIS



           **#include <stdio.h>**
    
           **ssize_t getline(char **restrict** _lineptr_**, size_t *restrict** _n_**,**
                           **FILE *restrict** _stream_**);**
           **ssize_t getdelim(char **restrict** _lineptr_**, size_t *restrict** _n_**,**
                           **int** _delim_**, FILE *restrict** _stream_**);**
    
       Feature Test Macro Requirements for glibc (see
       feature_test_macros(7)):
    
           **getline**(), **getdelim**():
               Since glibc 2.10:
                   _POSIX_C_SOURCE >= 200809L
               Before glibc 2.10:
                   _GNU_SOURCE
    


## DESCRIPTION



           **getline**() reads an entire line from _stream_ , storing the address of
           the buffer containing the text into _*lineptr_.  The buffer is null-
           terminated and includes the newline character, if one was found.
    
           If _*lineptr_ is set to NULL before the call, then **getline**() will
           allocate a buffer for storing the line.  This buffer should be
           freed by the user program even if **getline**() failed.
    
           Alternatively, before calling **getline**(), _*lineptr_ can contain a
           pointer to a malloc(3)-allocated buffer _*n_ bytes in size.  If the
           buffer is not large enough to hold the line, **getline**() resizes it
           with realloc(3), updating _*lineptr_ and _*n_ as necessary.
    
           In either case, on a successful call, _*lineptr_ and _*n_ will be
           updated to reflect the buffer address and allocated size
           respectively.
    
           **getdelim**() works like **getline**(), except that a line delimiter
           other than newline can be specified as the _delimiter_ argument.  As
           with **getline**(), a delimiter character is not added if one was not
           present in the input before end of file was reached.
    


## RETURN VALUE



           On success, **getline**() and **getdelim**() return the number of
           characters read, including the delimiter character, but not
           including the terminating null byte ('\0').  This value can be
           used to handle embedded null bytes in the line read.
    
           At end of file, both functions return -1 with the file stream end-
           of-file indicator set.  On error, both functions return -1 with
           the file stream error indicator set, and _errno_ is set to indicate
           the error.
    
           If _*lineptr_ was set to NULL before the call, then the buffer
           should be freed by the user program even on failure.
    


## ERRORS



           **EINVAL** Bad arguments (_n_ or _lineptr_ is NULL, or _stream_ is not
                  valid).
    
           **ENOMEM** Allocation or reallocation of the line buffer failed.
    


## ATTRIBUTES



           For an explanation of the terms used in this section, see
           attributes(7).
           ┌──────────────────────────────────────┬───────────────┬─────────┐
           │ **Interface** │ **Attribute** │ **Value** │
           ├──────────────────────────────────────┼───────────────┼─────────┤
           │ **getline**(), **getdelim**()                │ Thread safety │ MT-Safe │
           └──────────────────────────────────────┴───────────────┴─────────┘
    


## STANDARDS



           POSIX.1-2008.
    


## EXAMPLES



           #define _GNU_SOURCE
           #include <stdio.h>
           #include <stdlib.h>
    
           int
           main(int argc, char *argv[])
           {
               FILE *stream;
               char *line = NULL;
               size_t size = 0;
               ssize_t nread;
    
               if (argc != 2) {
                   fprintf(stderr, "Usage: %s <file>\n", argv[0]);
                   exit(EXIT_FAILURE);
               }
    
               stream = fopen(argv[1], "r");
               if (stream == NULL) {
                   perror("fopen");
                   exit(EXIT_FAILURE);
               }
    
               while ((nread = getline(&line, &size, stream)) != -1) {
                   printf("Retrieved line of length %zd:\n", nread);
                   fwrite(line, nread, 1, stdout);
               }
    
               free(line);
               fclose(stream);
               exit(EXIT_SUCCESS);
           }
    


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