How to print a number with two dots in the C language?

The problem is when I run this code

#include <stdio.h>
#include <string.h>

int main()
{
    double motorcyclePrice;

    scanf("%f", &motorcyclePrice);

    printf("The motorcycle of the brand %s it's %lf.", motorcycleBrand, motorcyclePrice);

    return 0;
}

The output of the print if I put "1.000.000" it will be "1.000000", so how can I set the output to be the same as input? I tried it with int, float and double and still the same...

Solution

In my earlier comment, I observed that you need a lot of things working in your favour to get the result you desire.

You need to set the locale to a locale other than the "C" or "POSIX" locale.
Using the empty string as the locale in a call to setlocale() means that the program should use the locale specified in the environment.
You need a locale that sets the 'radix character' (decimal point).
You need a locale that sets the 'grouping character'.
You need a version of printf() that recognizes the ' format modifier.
You also need a version of scanf() that permits the grouping character in the input, even though neither Standard C nor POSIX requires this.

So, the input parsing is extremely problematic — you need something other than Standard C scanf() to do that job.

You can generate the output if the locale is set up correctly.

Demo program:

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

int main(void)
{
    double price;
    setlocale(LC_ALL, "");
    if (scanf("%lf", &price) != 1)
        return 1;
    printf("%'.2f\n", price);
    return 0;
}

On a Mac running macOS Catalina (10.15.7), with LANG=en_US.UTF-8 in the environment, I can enter 1234567.89 and get the output 1,234,567.89. It wasn't until I tried an exhaustive test of the locales in /usr/share/locale that I found some locales that use , as the decimal point and . as the grouping character — none of de_DE.UTF-8, fr_FR.UTF-8, es_ES.UTF-8, pt_PT.UTF-8, it_IT.UTF-8 set the grouping character.

My test program is called pr17.

$ for locale in $(cd /usr/share/locale; ls -d *.UTF-8)
> do echo "$locale: $(LANG=$locale ./pr17 <<< '1234567,89')"
> done
af_ZA.UTF-8: 1.234.567,89
am_ET.UTF-8: 1,234,567.00
be_BY.UTF-8: 1 234 567,89
bg_BG.UTF-8: 1 234 567,89
ca_ES.UTF-8: 1234567,89
cs_CZ.UTF-8: 1 234 567,89
da_DK.UTF-8: 1.234.567,89
de_AT.UTF-8: 1234567,89
de_CH.UTF-8: 1234567,89
de_DE.UTF-8: 1234567,89
el_GR.UTF-8: 1.234.567,89
en_AU.UTF-8: 1,234,567.00
en_CA.UTF-8: 1,234,567.00
en_GB.UTF-8: 1,234,567.00
en_IE.UTF-8: 1,234,567.00
en_NZ.UTF-8: 1,234,567.00
en_US.UTF-8: 1,234,567.00
es_ES.UTF-8: 1234567,89
et_EE.UTF-8: 1 234 567,89
eu_ES.UTF-8: 1234567,89
fi_FI.UTF-8: 1.234.567,89
fr_BE.UTF-8: 1234567,89
fr_CA.UTF-8: 1234567,89
fr_CH.UTF-8: 1234567,89
fr_FR.UTF-8: 1234567,89
he_IL.UTF-8: 1,234,567.00
hr_HR.UTF-8: 1234567,89
hu_HU.UTF-8: 1 234 567,89
hy_AM.UTF-8: 1 234 567,89
is_IS.UTF-8: 1 234 567,89
it_CH.UTF-8: 1234567,89
it_IT.UTF-8: 1234567,89
ja_JP.UTF-8: 1,234,567.00
kk_KZ.UTF-8: 1 234 567,89
ko_KR.UTF-8: 1,234,567.00
lt_LT.UTF-8: 1 234 567,89
nl_BE.UTF-8: 1234567,89
nl_NL.UTF-8: 1234567,89
no_NO.UTF-8: 1.234.567,89
pl_PL.UTF-8: 1 234 567,89
pt_BR.UTF-8: 1.234.567,89
pt_PT.UTF-8: 1234567,89
ro_RO.UTF-8: 1 234 567,89
ru_RU.UTF-8: 1 234 567,89
sk_SK.UTF-8: 1 234 567,89
sl_SI.UTF-8: 1234567,89
sr_YU.UTF-8: 1 234 567,89
sv_SE.UTF-8: 1 234 567,89
tr_TR.UTF-8: 1234567,89
uk_UA.UTF-8: 1 234 567,89
zh_CN.UTF-8: 1,234,567.00
zh_HK.UTF-8: 1,234,567.00
zh_TW.UTF-8: 1,234,567.00
$

The input string uses a comma; when the radix character is ., it means that the ,89 is left in the input for further processing.

Your mileage will vary. Let me know your operating system and C library if scanf() supports the grouping character in the input.

Note that you're not supposed to process the output of ls because of possible spaces, newlines and assorted other 'gotcha' characters that can appear in file names. However, I checked that it would be safe for me before using it. YMMV!