getc(), getchar() — Read a character

Standards

Standards / Extensions	C or C++	Dependencies
ISO C POSIX.1 XPG4 XPG4.2 C99 Single UNIX Specification, Version 3	both

Format

#include <stdio.h>

int getc(FILE *stream);
int getchar(void);

General description

Reads a single character from the current stream position and advances the stream position to the next character. The getchar() function is identical to getc(stdin).

The getc() and fgetc() functions are identical. However, getc() and getchar() are provided in a highly efficient macro form. For performance purposes, it is recommended that the macro forms be used rather than the functional forms or fgetc(). By default, stdio.h provides the macro versions of these functions.

However, to get the functional forms, do one or more of the following:

For C only: do not include stdio.h.
Specify #undef, for example, #undef getc
Surround the call statement by parentheses, for example, (getc)

getc() and getchar() are not supported for files opened with type=record or type=blocked.

getc() and getchar() have the same restriction as any read operation for a read immediately following a write or a write immediately following a read. Between a write and a subsequent read, there must be an intervening flush or reposition. Between a read and a subsequent write, there must also be an intervening flush or reposition unless an EOF has been reached.

If the application is not multithreaded, then setting the _ALL_SOURCE_NO_THREADS feature test macro may improve performance of the application, because it allows use of the inline version of this function.

Special behavior for POSIX: In a multithreaded C application that uses POSIX(ON), in the presence of the feature test macro, _OPEN_THREADS, these macros are in an #undef status because they are not thread-safe.

Note: Because the getc() macro reevaluates its input argument more than once, you should never pass a stream argument that is an expression with side effects.

Returned value

getc() and getchar() return the character read.

A returned value of EOF indicates either an error or an EOF condition. If a read error occurs, the error indicator is set. If an EOF is encountered, the EOF indicator is set.

Use ferror() or feof() to determine whether an error or an EOF condition occurred. Note that EOF is only reached when an attempt is made to read past the last byte of data. Reading up to and including the last byte of data does not turn on the EOF indicator.

Example

CELEBG02

⁄* CELEBG02                                      

   This example gets a line of input from the stdin stream.                     
   You can also use getc(stdin) instead of &getchar. in the for                 
   statement to get a line of input from stdin.                                 
                                                                                
 *⁄                                                                             
#include <stdio.h>                                                              
                                                                                
#define LINE 80                                                                 
                                                                                
int main(void)                                                                  
{                                                                               
  char buffer[LINE+1];                                                          
  int i;                                                                        
  int ch;                                                                       
                                                                                
  printf( "Please enter string\n" );                                            
                                                                                
  ⁄* Keep reading until either:                                                 
     1. the length of LINE is exceeded  or                                      
     2. the input character is EOF  or                                          
     3. the input character is a new-line character                             
   *⁄                                                                           
                                                                                
  for ( i = 0; ( i < LINE ) && (( ch = getchar()) != EOF) &&                    
               ( ch !='\n' ); ++i )                                             
    buffer[i] = ch;                                                             
                                                                                
  buffer[i] = '\0';  ⁄* a string should always end with '\0' ! *⁄               
                                                                                
  printf( "The string is %s\n", buffer );                                       
}

Output

Please enter string
hello world
The string is hello world