I got an Interview question , What happens when we allocate large chunk of memory using malloc() inside an infinite loop and don't free() it. I thought of checking the condition with NULL should work when there is no enough memory on heap and it should break the loop , But it didn't happen and program terminates abnormally by printing killed . Why is this happening and why it doesn
我遇到了一个采访问题,当我们在无限循环内使用malloc()分配大块内存并且不free()时,会发生什么情况。 我认为用NULL检查条件应该在堆中没有足够的内存时工作,并且它应该打破循环,但是它没有发生,程序通过打印killed异常终止。 为什么会发生这种情况,以及为什么在没有内存分配的情况下它不执行if部分(我是指malloc()失败时)? 这是什么行为? 我的代码是: #include<stdio.h> #include<stdlib.h> in
I know that it's a common convention to pass the length of dynamically allocated arrays to functions that manipulate them: void initializeAndFree(int* anArray, size_t length); int main(){ size_t arrayLength = 0; scanf("%d", &arrayLength); int* myArray = (int*)malloc(sizeof(int)*arrayLength); initializeAndFree(myArray, arrayLength); } void initializeAndFree(int* anArray
我知道将动态分配数组的长度传递给操作它们的函数是一个常见惯例: void initializeAndFree(int* anArray, size_t length); int main(){ size_t arrayLength = 0; scanf("%d", &arrayLength); int* myArray = (int*)malloc(sizeof(int)*arrayLength); initializeAndFree(myArray, arrayLength); } void initializeAndFree(int* anArray, size_t length){ int i = 0; for (i = 0; i < length;
First of all I noticed when I malloc memory vs. calloc the memory footprint is different. I am working with datasets of several GB. It is ok for this data to be random. I expected that I could just malloc a large amount of memory and read whatever random data was in it cast to a float. However, looking at the memory footprint in the process viewer the memory is obviously not being claimed (v
首先我注意到当我malloc内存与calloc的内存占用是不同的。 我正在处理几个GB的数据集。 这些数据是随机的。 我期望我可以malloc大量的内存,并读取任何随机数据被转换为浮点数。 但是,在进程查看器中查看内存占用情况时,显然不会声明内存(相比calloc,我在这里看到的是较大的脚印)。 我运行一个循环来将数据写入内存,然后我看到内存占用率攀升。 我是否正确地说,在我初始化它之前,内存没有被实际声明? 最后,当
I'm doing a research with different nosql caches/databases. The following performance test was done with C# mongo driver 1.8.3.9 and ServiceStack.Redis 3.9.57.0. MongoDB 2.4 Redis 2.6.16 private List<string> GetListStrings() { var list = new List<string>(count); for (int i = 0; i < count; i++) { list.Add(Guid.NewGuid().ToString()); } return li
我正在用不同的nosql缓存/数据库进行研究。 使用C#mongo驱动程序1.8.3.9和ServiceStack.Redis 3.9.57.0完成以下性能测试。 MongoDB 2.4 Redis 2.6.16 private List<string> GetListStrings() { var list = new List<string>(count); for (int i = 0; i < count; i++) { list.Add(Guid.NewGuid().ToString()); } return list; } Mongo测试方法 public class TestStrings {
I am trying to find what is the combination of gcc flags to use when testing strict C90 conformance. According to previous post: GCC options for strictest C code?, I should only need a --std=c90. However here is what I tried: $ cat t.c #include <stdint.h> /* added in C99 */ int main() { uint64_t t; return 0; } $ gcc -std=c90 -ansi -pedantic t.c The above does work well (no warni
我试图在测试严格的 C90一致性时找到使用gcc标志的组合。 根据之前的文章:最严格C代码的GCC选项?,我应该只需要一个--std = c90。 但是,这是我试过的: $ cat t.c #include <stdint.h> /* added in C99 */ int main() { uint64_t t; return 0; } $ gcc -std=c90 -ansi -pedantic t.c 上面的工作很好(没有警告/错误产生)。 有谁知道: gcc标志符合严格的ISO / IEC 9899:1990标准 一个不同的编译器
I was coding on my project when I discovered that the anonymous structs I've been using for a while are actually only available in C11, not C99, the standard I want to code against. Given the following code: struct data { int a; struct { int b; int c; }; }; int main() { struct data d; d.a = 0; d.b = 1; d.c = 2; return 0; } This code should
当我发现我使用了一段时间的匿名结构实际上只在C11中可用,而不是C99时,我正在对我的项目进行编码,这是我想要编写的标准。 给出以下代码: struct data { int a; struct { int b; int c; }; }; int main() { struct data d; d.a = 0; d.b = 1; d.c = 2; return 0; } 此代码只应在C11中编译(或者如果编译器扩展提供此功能并且已启用)。 所以让我们看看不同编译器的结
Trying to compile SDL on MAC using XCode and C Language While trying to compile my program, the following error occurs: Undefined symbols for architecture x86_64: "_SDL_main", referenced from: -[SDLMain applicationDidFinishLaunching:] in SDLMain.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) If your
尝试使用XCode和C语言在MAC上编译SDL 在尝试编译我的程序时,发生以下错误: 体系结构x86_64的未定义符号:“_SDL_main”,引用自: - SDLMain.o中的[SDLMain applicationDidFinishLaunching:] ld:体系结构x86_64未找到符号ngng:错误:linker命令失败,退出代码1(使用-v to请参阅调用) 如果您的主程序名为Main.cpp ,请尝试像这样编译它: g++ Main.cpp -o main $(sdl2-config --cflags --libs) 并且sdl2-config将生
For some reason i get an error message after compiling a .c program. 11 warnings generated. Undefined symbols for architecture x86_64: "_main", referenced from: implicit entry/start for main executable ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) My date.c: #include "date.h" #include <stdlib.h>
出于某种原因,编译.c程序后出现错误消息。 产生了11个警告。 体系结构x86_64的未定义符号:“_main”,引用来自:隐式条目/ start for main可执行文件ld:找不到体系结构x86_64的符号clang:error:链接器命令失败,退出代码1(使用-v查看调用) 我的date.c: #include "date.h" #include <stdlib.h> #include <stdio.h> #include <string.h> struct date { char *day; char *month; char *year; }
Is it possible to avoid the entry point (main) in a C program. In the below code, is it possible to invoke the func() call without calling via main() in the below program ? If Yes, how to do it and when would it be required and why is such a provision given ? int func(void) { printf("This is func n"); return 0; } int main(void) { printf("This is main n"); return 0; } If y
是否有可能避免C程序中的入口点(main)。 在下面的代码中,是否可以在不通过main()调用下面的程序的情况下调用func()调用? 如果是,如何去做,什么时候需要,为什么会有这样的规定? int func(void) { printf("This is func n"); return 0; } int main(void) { printf("This is main n"); return 0; } 如果你使用的是gcc,我发现一个线程说你可以使用-e命令行参数来指定一个不同的入口点; 所以你可
I'm trying to use F# to construct a query against a database, but I can't get even the simplest of queries to compile. I can construct a C# query like this: from c in Categories select c Everything works fine. However, when I try to do what should be the same thing in F#: query { for c in Categories do select c } I get the following error: Invalid use of a type name and/o
我试图用F#来构建一个针对数据库的查询,但是我无法得到最简单的查询来编译。 我可以像这样构造一个C#查询: from c in Categories select c 一切正常。 但是,当我尝试在F#中执行相同的操作时: query { for c in Categories do select c } 我收到以下错误: 无效使用类型名称和/或对象构造函数。 如有必要,使用'new'并将构造函数应用于其参数,例如' new Type(args) '。 所需的签名是