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From: Carl Fredrik Forsberg <Carl DOT Fredrik DOT Forsberg AT ngi DOT no>
To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject: FW: Printing long int in C program under cygwin64
Date: Wed, 24 May 2017 12:00:16 +0000
Message-ID: <6f28f46906804c6f8f6b4b861e202492@CASMBX02.oslo.ngi.no>
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I am experiencing problems printing long int values under cygwin64 installed on a Windows 10 machine.

Below is a test program followed by its output to demonstrate the problem. The program was initially written to demonstrate the output from lrint(), and developed further to demonstrate to myself how negative integers are tackled by printf type specifiers (e.g. %li, %ld etc).

My understanding is that lrint() should return a long int. However I am unable to get printf to print the correct number. Instead its output is treated as an unsigned integer.
Any  help or hints would be much appreciated.

Regards
Carl Fredrik

#include <stdio.h>      /* printf */
#include <math.h>       /* lrint */

int main ()
{
  char text[64];
  printf ( "int -2 = %i\n", -2 );
  printf ( "int -1 = %i\n", -1 );
  printf ( "int 0 = %i\n", 0 );
  printf ( "int 1 = %i\n", 1 );
  printf ( "long int -2 = %li\n", -2 );
  printf ( "long int -1 = %li\n", -1 );
  printf ( "type cast -1 = %li\n", (long int)-1 );
  printf ( "type cast lrint(-1.0) = %li\n", (long int)lrint(-1.0) );
  printf ( "lrint(-1.0) = %li\n", lrint(-1.0) );
  printf ( "lrint(1.0) = %li\n", lrint(1.0) );
  printf ( "long int 0 = %li\n", 0 );
  printf ( "long int 1 = %li\n", 1 );
  sprintf( text,"long int -1 = %li", -1 );
  printf ( "Via sprintf: %s\n", text);
  printf ( "size of long int: %i\n", sizeof(long int));
  printf ( "size of int: %i\n", sizeof(int));
  return 0;
}


compiled by:
gcc lrint_test.c -o lrint_test.exe

Output:

int -2 = -2
int -1 = -1
int 0 = 0
int 1 = 1
long int -2 = 4294967294
long int -1 = 4294967295
type cast -1 = -1
type cast lrint(-1.0) = 4294967295
lrint(-1.0) = 4294967295
lrint(1.0) = 1
long int 0 = 0
long int 1 = 1
Via sprintf: long int -1 = 4294967295
size of long int: 8
size of int: 4


gcc version:
gcc (GCC) 5.4.0
Copyright (C) 2015 Free Software Foundation, Inc.


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