Use this tag for questions about entry points to executables (programs); e.g., the "main()" function in most programming languages. If your question is programming language specific, tag that: language as well e.g. C, C++, Java etc.
Questions tagged [program-entry-point]
2997 questions
114
votes
9 answers
Is ‘int main;’ a valid C/C++ program?
I ask because my compiler seems to think so, even though I don’t.
echo 'int main;' | cc -x c - -Wall
echo 'int main;' | c++ -x c++ - -Wall
Clang issues no warning or error with this, and gcc issues only the meek warning: 'main' is usually a function…
Geoff Nixon
- 4,697
- 2
- 28
- 34
114
votes
3 answers
`if __name__ == '__main__'` equivalent in Ruby
I am new to Ruby. I'm looking to import functions from a module that contains a tool I want to continue using separately. In Python I would simply do this:
def a():
...
def b():
...
if __name__ == '__main__':
a()
b()
This allows…
Imagist
- 18,086
- 12
- 58
- 77
108
votes
7 answers
Why is argc not a constant?
int main( const int argc , const char[] const argv)
As Effective C++ Item#3 states "Use const whenever possible", I start thinking "why not make these 'constant' parameters const"?.
Is there any scenario in which the value of argc is modified in a…
Dinushan
- 2,067
- 6
- 30
- 47
98
votes
7 answers
How can a program with a global variable called main instead of a main function work?
Consider following program:
#include
int main = ( std::cout << "C++ is excellent!\n", 195 );
Using g++ 4.8.1 (mingw64) on Windows 7 OS, the program compiles and runs fine, printing:
C++ is excellent!
to the console. main appears to be…
Destructor
- 14,123
- 11
- 61
- 126
94
votes
8 answers
What is the Eclipse shortcut for "public static void main(String args[])"?
I know a cool shortcut for System.out.println(): sysout Ctrl + Space.
Is there something similar for public static void main(String args[])?
user244333
92
votes
6 answers
Can argc be zero on a POSIX system?
Given the standard definition for the main program:
int main(int argc, char *argv[]) {
...
}
Under which circumstances can argc be zero on a POSIX system?
Sylvain Leroux
- 50,096
- 7
- 103
- 125
85
votes
4 answers
Is char *envp[] as a third argument to main() portable
In order to get an environment variable in a C program, one could use the following:
getenv()
extern char **environ;
But other than the above mentioned, is using char *envp[] as a third argument to main() to get the environment variables…
Sangeeth Saravanaraj
- 16,027
- 21
- 69
- 98
84
votes
10 answers
Is it safe to rename argc and argv in main function?
A lot of programs use standard names for a number of arguments and arrays of strings. The prototype of main function looks like: int main(int argc, char *argv[]);. But would I break something if I choose custom names for these variables?
E.g. int…
yanpas
- 2,155
- 1
- 17
- 26
82
votes
7 answers
WINMAIN and main() in C++ (Extended)
Right, I have looked at this post: Difference between WinMain,main and DllMain in C++
I now know that WINMAIN is used for window applications and main() for consoles. But reading the post doesn't really tell me why exactly what is the difference.
I…
Danny
- 9,199
- 16
- 53
- 75
80
votes
2 answers
Compile and run program without main() in C
I'm trying to compile and run following program without main() function in C. I have compiled my program using the following command.
gcc -nostartfiles nomain.c
And compiler gives warning
/usr/bin/ld: warning: cannot find entry symbol _start;…
msc
- 33,420
- 29
- 119
- 214
74
votes
3 answers
How to access global variables
How do I access a variable that was declared/init in my main.go in a different .go package/file? Keeps telling me that the variable is undefined (I know that global variables are bad but this is just to be used as a timestamp)
in main.go
var…
Nighthee
- 1,329
- 3
- 13
- 14
74
votes
10 answers
Multiple Main Functions
I'm a bit new at this so bear with me. I'm currently learning C# and Java and one of their similarities is that the main function needs to be encapsulated within a class. For example
public class HelloWorld {
public static void main(String[]…
Ben
- 1,233
- 2
- 14
- 17
73
votes
5 answers
Using Spring 3 autowire in a standalone Java application
Here is my code:
public class Main {
public static void main(String[] args) {
Main p = new Main();
p.start(args);
}
@Autowired
private MyBean myBean;
private void start(String[] args) {
…
mike27
- 733
- 1
- 6
- 4
71
votes
22 answers
Could not find or load main class with a Jar File
I'm trying to load a jar using
@echo off
java -jar Test.jar
pause
With the manifest of
Manifest-Version: 1.0
Main-Class: classes.TestClass
In the Jar directory, I can clearly see a classes\TestClass file when I extract it.
Edit: classes.TestClass…
Austin
- 4,801
- 6
- 34
- 54
70
votes
17 answers
Why main() in C++ cannot be inlined?
I was reading the C++ FAQs and I noticed one sentence.
main() cannot be inline.
Why is this?
jon
- 615
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