so I was having a problem with a big code that uses strings and file names. I had many issues with it and I addedd some printf in bwtween to Keep check of how the Code works. I couldnt get anything in the output so i decided to take to old good "hello world" program to see if printf was the issue.
so here is the Code :
#include <stdio.h>
int main (void){
printf("hello world\n");
}
I thought Maybe it is a Buffering issue, so I have tried some variations like :
#include <stdio.h>
int main (void){
setvbuf(stdout, NULL, _IOLBF, 0);
printf("hello world\n");
}
and
#include <stdio.h>
int main (void){
printf("hello world\n");
setbuf(stdout, NULL);
}
still Nothing is printed. any idea on how to find the issue? ps: I am writing on Notepad and i execute using gcc on terminal. gcc is installed just fine and I am working on Windows.
I checked the file's path and it is fine. The command I use is gcc filename.c
I am new and I know how to color output only in Unix/Linux systems:
#include <stdio.h>
int main(void) {
printf("\033[1;31mRed Message\033[0m.");
}
But this is not works in Windows cmd.exe, only in Unix terminal.
I am writing cross-platform app and want to know how can I do this in Windows cmd.exe too.
This also does not works:
1.
#include <stdio.h>
int main(void) {
printf("%c[1;31mRed Message%c[0m", 27, 27);
}
2.
#include <stdio.h>
int main(void) {
printf("[1;31m Red Message [0m");
}
This works, but I think this is just a bug:
If I type system(""); before printf then it works.
#include <stdio.h>
int main(void) {
system("");
printf("\033[1;31m Red Message \033[0m");
}
Thanks
If you want to make your library crossplatform, I would use the following approach:
Have a library, with the same functions, let's say:
void printInRed(const char* string). (In a headerfile)
After that you write two or more implementations.
One for windows:
//TODO: Errorchecking
void printInRed(const char* string){
HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
//TODO: Extract magic number
//See https://stackoverflow.com/a/4053879/13912132
SetConsoleTextAttribute(hConsole, 12);
puts(string);
}
And another one for unix-like OS:
//TODO: Errorchecking
void printInRed(const char* string){
printf("\033[1;31m%s\033[0m.", string);
}
Then you can check at compile time, which version to compile.
The first approach is to use #ifdefs, but this will make the code a bit messy.
Another approach would be to use a build-system like CMake to select at build time, which one to build. A buildsystem requires a bit of learning, but will help you to make maintaining a crossplatform library simpler.
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.
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");
}
I wrote little program to print "Hello world" in C. I'm not a C programmer, but I liked to try it. In my program there is an error. Please tell me what is it?
This is my program:
int main(){
printf("Hello World");
}
I wrote this with my Java Experiences. I can't find what is wrong.
You can't directly use printf() function as in Java. You should tell the compiler that you are going to use the input/output stream. You can tell it in this line:
#include <stdio.h>
and also you should enter this line at the end of the source code:
return 0;
this will tell the compiler :
"If the program succeed It will return 0 otherwise It will return any other number"
This means if your program is successful main() function will return 0. Then the compile know the program is Ok.
Then at last your complete code is:
#include <stdio.h>
int main() {
printf("Hello world");
return 0;
}
To compile this and see the word "Hello World", just save this file as a .c file and Open cmd in your program directory and type
gcc hello.c -o hello && hello
(Replace the 'hello.c' with your filename, and 'hello' with the name you want to put with your .exe file)
Remember My computer is Windows. And this compile code is for windows. If your OS is UNIX like OS. then use this code to compile:
gcc hello.c -o hello
./hello
A full hello world program in C:
#include <stdio.h>
int main(void) {
printf("Hello World\n");
return 0;
}
Then compile (assuming gcc) and execute it:
gcc -o test test.c
./test
First, you have to use a header file.
#include <stdio.h>
What that does is bring up a header file with a bunch of commands in them. That will make it recognize the "printf" piece of code.
Next, you have to close your program. By not having a closing statement, the program will not compile because it doesn't know if that is the end of the code. Use this at the end of your program...
return 0;
That closes the program, meaning that the compiler can stop looking for other code. You may also want to look at some programming manuals (there are dozens of free online ones) to learn about the syntax.
One last thing: Most pieces of C code require a semicolon at the end. This is not true for the "int main" statement, nor is it for the header file which I have defined above. The "return" function that closes the program, does however, need a semicolon.
Hoped this helped.
Should also include a pause at the end:
#include <stdio.h>
int main(void) {
printf("Hello World\n");
//Read a character from the console
getchar();
return 0;
}
Just like import in Java programs, in here you have to include libraries you're using in your program. You have used library function printf, but not included stdio.h.
I agree there are many ways to write one of the simplest way is
#include<stdio.h>
int main(void){
printf("Hello World\n");
return 0;
}
You can even use different ways as suggested above.
You should first look at the structure of "main". Try to understand the various parts as already explained so well in the above answers.
"#include" : The preprocessing directives to be included in the program. But why? Because you are trying to use the functions defined inside them.
int : The return type of "main" program. But why? Because the function calling "main" needs to know if the "main" program has functioned correctly.
main : The entry point of your code. Dont ask why here :-)
main( void ) : To tell the compiler that we are not passing any arguments to program "main"
return 0 : Beacuse you promised "main" that you will return something if "main" will function properly.
Finally the code:
#include <stdio.h>
int main( void )
{
printf( "Hello World\n" ) ; //Notice the '\n' here. Good coding practice.
return 0 ;
}
#include <stdio.h> //Pre-processor commands<br/>
void main() //Starting point of the program<br/>{ //Opening Braces
printf("Hello World\n"); //Print Hello World on the screen<br/>
return 0;
} //Ending Braces
Check it once it will work, I have written it with comments:
#include<stdio.h> //Pre-processor commands
void main() {
printf("Hello World\n"); //Print Hello World on the screen
}
A full hello world program in C:
#include <stdio.h>
int main(void) {
printf("Hello World\n");
return 0;
}
Then compile (assuming gcc) and execute it:
gcc -o test test.c
./test
You can't use printf() function as in Java. You have to tell the compiler what you are going to use.
You can tell this as follows:-
#include <stdio.h>
You must enter this line in last:-
return 0;
Then Your complete code is:-
#include <stdio.h>
int main(){
printf("Hello World");
return 0;
}
For compiling this and see the word "Hello World", just save this file as a .c file and Open cmd in your program directory and type:-
gcc hello.c -o hello && hello
(Replace the 'hello.c' with your filename, and 'hello' with the name you want to put with your .exe file)
Remember My computer is Windows. So I can compile only for Windows OS.
#include <stdio.h>
int main() {
// printf, used to print (display) Hello World
printf("Hello World ! ");
// return 0, as the main function is of type int so it must return an integer value
return 0;
}