SetConsoleScreenBufferInfoEx works different from SetConsoleTextAttribute - c

Question

Recently I tried to print text in C with underscore. My console doesn't support ANSI escape character so I tried using DBCS, which my console does support. To do so, I had to change the console text attributes. At the beginning I used SetConsoleTextAttribute to change it but later when I wanted to remember the color and ONLY change the underscore I started using GetConsoleScreenBufferInfoEx and SetConsoleScreenBufferInfoEx to also get the previous attributes. That's when I noticed that when I use the former, it only affects the text which I print after the call, and in the case of the latter, I also change the attributes of the previous text.
For example, I wrote 2 short codes and compiled them.
Code 1:
#include <Windows.h>
#include <stdio.h>
int main()
{
printf("Code 1:\n");
HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
DWORD mode = 0;
int flag = 1;
flag &= GetConsoleMode(out, &mode);
flag &= SetConsoleMode(out, mode | ENABLE_LVB_GRID_WORLDWIDE);
//7 is the default foreground - gray
SetConsoleTextAttribute(out, 7 | COMMON_LVB_UNDERSCORE);
printf("Hello World! 1==%d", flag);
getchar();
SetConsoleTextAttribute(out, 7);
printf("Goodbye World! 1==%d", flag);
getchar();
return 0;
}
And code 2:
#include <Windows.h>
#include <stdio.h>
typedef CONSOLE_SCREEN_BUFFER_INFOEX CSBI;
int main()
{
printf("Code 2:\n");
HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
DWORD mode = 0;
int flag = 1;
flag &= GetConsoleMode(out, &mode);
flag &= SetConsoleMode(out, mode | ENABLE_LVB_GRID_WORLDWIDE);
CSBI csbi = { 0 };
csbi.cbSize = sizeof(csbi);
flag &= GetConsoleScreenBufferInfoEx(out, &csbi);
csbi.wAttributes |= COMMON_LVB_UNDERSCORE;
flag &= SetConsoleScreenBufferInfoEx(out, &csbi);
printf("Hello World! 1==%d", flag);
getchar();
csbi.wAttributes &= ~COMMON_LVB_UNDERSCORE;
flag &= SetConsoleScreenBufferInfoEx(out, &csbi);
printf("Goodbye World! 1==%d", flag);
getchar();
return 0;
}
the flag is to make sure that all function return TRUE
In the first code, 'Code 1' will remain without underscore, 'Hello World!' will have underscore, and 'Goodbye World!' won't have an underscore.
In the second code, everything will have underscore until I enter a new line, and then everything will lose their underscore.
Does anyone have an idea why is it like that? I though that they will do the same about console text attributes.
Thanks, Roy

Answer 1

In the second code, everything will have underscore until I enter a new line, and then everything will lose their underscore.
After my test, the final effect of the two pieces of code is the same.
Does anyone have an idea why is it like that? I though that they will do the same about console text attributes.
SetConsoleTextAttribute: Sets the attributes of characters written to
the console screen buffer by the WriteFile or WriteConsole function,
or echoed by the ReadFile or ReadConsole function. This function
affects text written after the function call.
SetConsoleScreenBufferInfoEx: Sets extended information about the
specified console screen buffer.
For the comment, on the properties of the console text, SetConsoleTextAttribute and SetConsoleScreenBufferInfoEx can achieve the same effect, such as changing the color of the text or add underscore.