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Why are recursive main() calls not allowed in C++? [duplicate]

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Possible Duplicates: restrictions on the main() function Is it legal to recurse into main() in C++? I read in C++ Primer that main is not allowed to be called recursively, and in some related questions here on SO it is indeed confirmed that it is illegal. But why is it illegal? As long as you avoid a stack overflow, what's the problem with calling main within itself? Well, the standard states: 3.6.1.3 "The function main shall not be used within a program." 5.2.2.9 "Recursive calls are permitted, except to the function named main" I guess it is beause main() is a special function used as the

Is there any way to distinguish the main Thread from any Threads that it spawns?

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问题 I know that the getName() function on the main thread will return the String main , but this can be changed with setName() . Is there any way to always determine the main thread of an application? 回答1: It seems that the main thread has an id of 1 as indicated by Thread.getId(): class test{ public static boolean isMainThread(){ return Thread.currentThread().getId() == 1; } public static void main(String[]args){ System.out.println(isMainThread()); new Thread( new Runnable(){ public void run(){

Multiprocessing with multiple arguments to function in Python 2.7

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问题 I'm trying to implement multiprocessing to speed up a replication loop, but cannot get it to work in Python27. This is a very simplified version of my program, based on the docs and other answers here at SO (e.g. Python multiprocessing pool.map for multiple arguments). I realize that there are a number of quesions on multiprocessing, but so far I haven't been able to solve this issue. Hopefully I haven't overlooked anything too trivial. Code import itertools from multiprocessing import Pool

How to test the main package functions in golang?

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I want to test a few functions that are included in my main package, but my tests don't appear to be able to access those functions. My sample main.go file looks like: package main import ( "log" ) func main() { log.Printf(foo()) } func foo() string { return "Foo" } and my main_test.go file looks like: package main import ( "testing" ) func Foo(t testing.T) { t.Error(foo()) } when I run go test main_test.go I get # command-line-arguments .\main_test.go:8: undefined: foo FAIL command-line-arguments [build failed] As I understand, even if I moved the test file elsewhere and tried importing from

Multiple main CPP files in VisualStudio?

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问题 I have a sample directory of some software, which contains multiple files with multiple main functions. May I assemble all of these files into single project, compile them and then run specific ones without getting main already defined error? Suppose I don't want to create separate project for each cpp file. UPDATE I need simple one-two-click solution (if it exists). I don't want to distribute files among folders or refactor files content. For example in Eclipse/Java you can right-click any

Why would you precede the main() function in C with a data type? [duplicate]

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问题 This question already has answers here : What should main() return in C and C++? (17 answers) Closed 4 years ago . Many are familiar with the hello world program in C: #include <stdio.h> main () { printf ("hello world"); return 0; } Why do some precede the main() function with int as in: int main() Also, I've seen the word void entered inside the () as in: int main(void) It seems like extra typing for nothing, but maybe it's a best practice that pays dividends in other situations? Also, why

Multiple main() methods in java

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问题 I was wondering what the effect of creating extra main methods would do to your code. For example, public class TestClass { public static void main (String[] args){ TestClass foo = new TestClass(); } } After the program initially starts up, foo will be created and it would have another public main method inside it. Will that cause any errors? 回答1: It will cause no errors. Just because you initialize an object, doesn't mean the main method gets executed. Java will only initially call the main

C++ what to code if i put a class after main() function

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I'm watching some video tutorials on C++ and i know you must define a function / class before it is used or called. But I like having my main() function at the top, and everything else below the main function. I know if i define a function below the main function I must declare it before it is used, but what about a class? What do I need to put above my main function to use my class below the main function. #include <iostream> using namespace std; int main() { ClassOne one; one.coolSaying(); return 0; } class ClassOne { public: void coolSaying() { cout << "Cool stuff yo!" << endl; } }; I tried

Using int Instead Of String: public static void main (int[] args)

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I was under the impression that the main method had to have the form "public static void main (String[] args){}", that you couldn't pass int[] arguments. However, in windows commandline, when running the following .class file, it accepted both int and string as arguments. For example, using this command will give the output "stringers": "java IntArgsTest stringers" My question is, why? Why would this code accept a string as an argument without an error? Here is my code. public class IntArgsTest { public static void main (int[] args) { IntArgsTest iat = new IntArgsTest(args); } public

Why doesn't Java's main use a variable length argument list?

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问题 I have a question about the syntax of the Java main declaration: public static void main (String[] args) Since you can pass a variable number of Strings when invoking the main function, shouldn't this be a variable length argument list rather than an array? Why would a command-line invocation of this method with a list of string parameters even work? (Unless there is behind-the-scenes processing that builds an array with the list of strings and then passes that array to the main method...?)