对于包含土耳其语字符的字符串，C printf 函数无法正确对齐字符串

Question

I have the following code to print some strings on the console in a left aligned format:

#include <stdio.h>
#include <locale.h>
#include <stdlib.h>

int main()
{
    printf("%s:\n", "Türkçe karakterler ile");
    printf("%-14s: \n", "Onaltılık");
    printf("%-14s: \n", "Onluk");
    printf("%-14s: \n", "İkilik");

    printf("\n%s:\n", "Türkçe karakterler olmadan");
    printf("%-14s: \n", "Onaltilik");
    printf("%-14s: \n", "Onluk");
    printf("%-14s: \n", "Ikilik");
}

I compiled this code with both gcc(7.3.0) and clang(6.0.0) on a Ubuntu 18.04 system.

The output is as follows:

Türkçe karakterler ile:
Onaltılık  : 
Onluk        : 
İkilik      : 

Türkçe karakterler olmadan:
Onaltilik     : 
Onluk         : 
Ikilik        :

As can be seen from the code in the first group of strings there are some Turkish characters such as 'ı' and 'İ'. There is no Turkish characters in the second group of strings.

The output of printf function is not correctly aligned for the strings that contain Turkish characters. The expected output is:

Türkçe karakterler ile:
Onaltılık     : 
Onluk         : 
İkilik        : 

Türkçe karakterler olmadan:
Onaltilik     : 
Onluk         : 
Ikilik        :

If I compile same code on a Windows system (Windows 7) with gcc (MinGW v5.1.1 inside CodeBlocks 17.2) the output is correct as follows:

Türkçe karakterler ile:
Onaltılık     :
Onluk         :
İkilik        :

Türkçe karakterler olmadan:
Onaltilik     :
Onluk         :
Ikilik        :

Can anyone help me to figure out what the problem is?

Answer 1

My guess is it's because your editor saved the source using UTF-8, which is a multi-byte encoding. The printf family of functions only deals with byte strings. That means every non-ASCII character will be counted as multiple characters by printf .

If it's like that you can work around the problem by printing the string, and then adding padding manually after using the * modifier when printing an empty string. The * modifier allows you to pass the width as an argument to printf .

Something like this:

printf("%s%*s: \n", "Onaltılık", 5, "");  // 5 = 14 - 9, where 9 is the number of "characters" in Onaltılık
printf("%s%*s: \n", "Onluk"    , 9, "");  // Dito for Onluk
printf("%s%*s: \n", "İkilik"   , 8, "");  // Dito for İkilik

Output:

Onaltılık     : 
Onluk         : 
İkilik        :