main

Why does Rust not have a return value in the main function, and how to return a value anyway?

由 谁都会走 提交于 2020-06-24 05:44:08
问题 In Rust the main function is defined like this: fn main() { } This function does not allow for a return value though. Why would a language not allow for a return value and is there a way to return something anyway? Would I be able to safely use the C exit(int) function, or will this cause leaks and whatnot? 回答1: As of Rust 1.26, main can return a Result : use std::fs::File; fn main() -> Result<(), std::io::Error> { let f = File::open("bar.txt")?; Ok(()) } The returned error code in this case

Problem with IntelliJ -> Cannot create class with name “Main”

由 百般思念 提交于 2020-05-23 10:33:09
问题 Title states my problem, i get this error message: Cannot Create Class Unable to parse template "Class" Error message: Selected class file name 'Main.java' mapped to not java file type 'Files supported via TextMate bundles' Anyone got any ideas on how I can solve this? 回答1: Please check the File Types. It looks like Main.java file name or extension was mapped to the wrong file type by accident ( Files supported via TextMate bundles ). Remove the invalid type mapping to fix the problem. The

Initialize/set char *argv[] inside main() in one line

由 回眸只為那壹抹淺笑 提交于 2020-05-12 03:45:06
问题 I want to initialize/set char *argv[] inside the main() so that I can use argv[1], argv[2]... later in my program. Up to now, I know how to do this in two ways: For int main() , use one line as: int main() { char *argv[] = {"programName", "para1", "para2", "para3", NULL}; } Note that, using NULL in the end is because the pointers in the argv array point to C strings, which are by definition NULL terminated. For int main(int argc, char* argv[]) , I have to use multiple lines as: int main(int

Initialize/set char *argv[] inside main() in one line

由 孤人 提交于 2020-05-12 03:44:05
问题 I want to initialize/set char *argv[] inside the main() so that I can use argv[1], argv[2]... later in my program. Up to now, I know how to do this in two ways: For int main() , use one line as: int main() { char *argv[] = {"programName", "para1", "para2", "para3", NULL}; } Note that, using NULL in the end is because the pointers in the argv array point to C strings, which are by definition NULL terminated. For int main(int argc, char* argv[]) , I have to use multiple lines as: int main(int

libdvbpsi源码分析(二)main函数

由 拥有回忆 提交于 2020-04-17 02:20:50
【推荐阅读】微服务还能火多久？>>> 从demon的dvbinfo.c中的main函数入口分析： 为了分析方便，此处将宏HAVE_SYS_SOCKET_H隔离的socket代码去掉，只关注libdvbpsi本身的实现。 1.数据结构的设计： 1.1、捕获器capture的数据结构设计如下： typedef struct dvbinfo_capture_s { fifo_t *fifo; fifo_t *empty; pthread_mutex_t lock; pthread_cond_t fifo_full; bool b_fifo_full; size_t size; /* prefered capture size */ params_t *params; bool b_alive; } dvbinfo_capture_t; 由数据结构可知，由于demo是本地的autotest，所以用有名管道fifo作测试。从命令行终端读入ts流文件，一个 线程不断将buffer中的数据push进入fifo，同时主线程不断从fifo pop出数据并解析，直到从fifo中读出的数据为0 1.2、dvbinfo_capture_t中的params_t 结构体 typedef struct params_s { /* parameters */ char *output; char *input;

TypeError: main() takes exactly 1 argument (0 given)

由 僤鯓⒐⒋嵵緔 提交于 2020-01-25 20:08:30
问题 I'm trying to create a main() in a class file in Python 2.7.11 and run it, but Python is claiming I need to pass main() an argument. def main(self): howManyBadCrops = BadCropsDetector() # My class # a bunch of stuff goes here that runs the module.... if __name__ == "__main__": main() Why is this happening? Here is my terminal output: Traceback (most recent call last): File "badCropsDetector.py", line 11, in <module> class BadCropsDetector: File "badCropsDetector.py", line 66, in

TypeError: main() takes exactly 1 argument (0 given)

由 为君一笑 提交于 2020-01-25 20:05:05
问题 I'm trying to create a main() in a class file in Python 2.7.11 and run it, but Python is claiming I need to pass main() an argument. def main(self): howManyBadCrops = BadCropsDetector() # My class # a bunch of stuff goes here that runs the module.... if __name__ == "__main__": main() Why is this happening? Here is my terminal output: Traceback (most recent call last): File "badCropsDetector.py", line 11, in <module> class BadCropsDetector: File "badCropsDetector.py", line 66, in

Are there advantages of declaring functions before, after or inside main()?

由 空扰寡人 提交于 2020-01-24 06:15:38
问题 I'm trying to learn C language for embedded systems. At the moment I'm learning the basics and couldn't find an answer to one of a fundamental question. When I wrote a simple C program I declared a function called maximum() in three ways. I will explain it by the following examples: 1-) Here in the below program the function is declared outside and before the main: #include <stdio.h> int maximum(int x, int y) { int z; z = (x >= y) ? x : y; return z; } int main(void) { int result = maximum(30,

Nested Static classes Java [duplicate]

由 旧巷老猫 提交于 2020-01-16 09:06:34
问题 This question already has answers here : Error - Illegal static declaration in inner class (3 answers) Closed 4 days ago . I am a beginner to java. I was practicing java nested classes when I run the given problem. Oracle JDK 11.0.5 Problem:- Whenever I try to run the compiler for the following code I run across the given errors. public class test { public class Outer{ static int out1; public static void display1() { System.out.println("\n\nIn outer one!"); System.out.println(out1); } public

Is the main() function odr-used?

由 只谈情不闲聊 提交于 2020-01-15 11:55:06
问题 Is the main() function odr-used? E.g in the simple program like this: int main() { } 回答1: No, it is not. Not in your simple program. [basic.def.odr] 3 A function whose name appears as a potentially-evaluated expression is odr-used if it is the unique lookup result or the selected member of a set of overloaded functions ([basic.lookup], [over.match], [over.over]), unless it is a pure virtual function and either its name is not explicitly qualified or the expression forms a pointer to member (
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