I am having a problem with a program of mine, as I cannot see the output display. Using a Dev C++ compiler to compile my C program, I debug it to see the output. However my program immediately terminates, so I can't see the output properly.
I ended my program with return 0, and Aldo tried getch(), but even with both endings my program terminates quick.
I want to know if my program endings are wrong, and if so what is the correct way to end a program?
you need the window stop to view the output, is it right?
if yes, include this library
#include <stdlib.h>
then add this line at the end of code:
system("PAUSE");
e.g
#include <stdlib.h>
#include <stdio.h>
int main()
{
/* do/print some thing*/
system("PAUSE");
}
Related
I dont get the strange behavior of gdb when I do step and it goes to printf.
#include <stdio.h>
#include <stdlib.h>
int main()
{
printf("Hello");
}
The debugging loads libraries I dont get what happens. It writes hundreds of line, I have to ctrl F to find my printf !
What happens and how to prevent this ?
Here is a picture of my terminal
I've been writing a Linux program that's meant to write non-English characters on the terminal, I've recently been porting it to Windows, and I've run into some issues, when trying to change the code page and the font of the terminal, having the symbolic constant _POSIX_C_SOURCE previously defined seems to change the behavior of the code, and makes it incapable of properly printing non-English characters, for reference, this is my code.
#include <windows.h>
#include <stdio.h>
int main()
{
SetConsoleCP(CP_UTF8)
SetConsoleOutputCP(CP_UTF8)
HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
CONSOLE_FONT_INFOEX cfie;
ZeroMemory(&cfie, sizeof(cfie));
cfie.cbSize = sizeof(cfie);
lstrcpyW(cfie.FaceName, L"Lucida Console");
SetCurrentConsoleFontEx(hStdOut, 0, &cfie);
printf("Ћирилични текст\n");
return 0;
}
This is what the program prints out depending on whether I do or don't define the constant in a command line argument while compiling.
C:\Users\User\Desktop>gcc test.c
C:\Users\User\Desktop>a.exe
Ћириличан текст
C:\Users\User\Desktop>gcc -D_POSIX_C_SOURCE=2 test.c
C:\Users\User\Desktop>a.exe
������������������ ����������
This is because outputting to standard output is done literally byte-by-byte when POSIX compliance is in effect. It uses a different implementation of what is done inside the printf function.
I ran a 4 line code and it compiled and linked without a hitch, but it refuses to print anything
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
char* a = "book";
printf("%s\n", a);
return 0;
}
After compiling it and running the executable, nothing happens.
No error in the code.
Just write getch(); or getchar() before return 0;
to holding the output screen.
getch() or getchar() will hold the ouput screen for getting the user's input.
Works fine for me.
You've tagged this with terminal; if you are running it from the terminal, you should see some output, in my experience.
If you are running from an IDE,
keep the window open using Kapil K.'s answer;
keep the window open using an IDE setting, if there is one; or
find out where your IDE is putting the executable file, and run that from a terminal.
This is my code. I'm completely aware that an endless loop results when executing directly. What I did was I compiled this code and then executed twice in the linux command line via ./a.out & twice. The first time the program executes, it runs fine and gives a decent file handle. When the first instance of the program is running in the background and I execute the second instance one minute later (via ./a.out &), the file handle returned is the exact same. I was expecting a negative return value for the second instance to indicate the first instance is using the file.
How do I solve this issue? I don't want to use buffered file functions like fopen/fread because the file I want to make is small and must be made at the beginning of the program before anything else happens in the code.
This is my code:
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(){
char* pidf="/testpid.del";
int lfp=open(pidf,O_WRONLY|O_CREAT|0x700);
printf("File handle = %d\n",lfp);
if (lfp ==-1){printf("Can't use PID file: %s\n",pidf);return -1;}
while(1){
sleep(1);
}
close(lfp);
}
Today , When i coding, met a question..my Code as follow:
#include<stdlib.h>
void main()
{
system("dir");
getch();
}
The question : The user Screen is nothing..Why ? where is my result?
If you want the output when using system, at least into something you can read in your application, you need to pipe the output:
system("dir > /tmp/output.txt");
FILE *f = fopen("/tmp/output.txt", "r");
char text[1024]; // max sizeof of 1 kb, any more and I'd consider using `malloc()` instead.
fread(text, 1, 1024, f);
printf("%s\n", text);
fclose(f);
There are some problems in your program, at least one of which has already been mentioned.
void main() should be int main(void).
As I recall, the Windows/DOS getch function is declared in <conio.h>; you should have a #include directive for it. Be aware that both <conio.h> and getch are non-standard.
Since main returns int, you should return an int result.
But none of these problems explain the problem you're seeing.
With these changes:
#include <stdlib.h>
#include <conio.h>
int main(void)
{
system("dir");
getch();
return 0;
}
This should work; it should show a directory listing of whatever directory your program runs in (which is determined by TC; I don't know the details).
It's possible that the program is running in an empty directory, which means the dir command wouldn't show any files, but it should still produce some output.
Try commenting out the system() call and adding a printf call (note the added #include <stdio.h>):
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
int main(void)
{
printf("Hello, world\n");
getch();
return 0;
}
This should open a console window, print "Hello, world" in it, and wait for you to type Enter.
If you still don't see any output (either no console window, or a console window with nothing in it), then you have a problem that's not related to the system() call. Most likely the problem has to do with the way you're using Turbo C (I presume that's what "TC" stands for).
The main function in every C program is supposed to return an int you are returning void
Change void to int:
#include<stdlib.h>
int main()
{
system("dir");
getch();
}
When I tested, the dir command ran in my console and printed to standard out.
May be he is the running the program directly in the Turbo C IDE and hence his output is not visible. If he runs the program directly from cmd line it works. I remember you need to run Alt - F5 or some other combination to see the output window in Turbo C++