Recent questions tagged C

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c - GCC is generating binaries filled with zeroes

I'm trying to figure out why the binaries generated by GCC are so large. Consider this empty program: int main ... consume all of my disk space? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - While with multiple conditions

Can somebody please explain why a while statement like while (ch != ' ' || ch != '' || ch != ' ') { ... } does not work as I expected? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Is NULL a pointer?

So, I had an argument with my professor earlier defending that NULL is not a pointer, but he kept on insisting ... so my last resort is here See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Pointer cast for use with qsort

This code snippet hand copied from a book I am reading: /* scmp: string compare of *p1 and *p2 */ int scmp(const void ... v1 = *(char **) p1 ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Can't assign -2147483648 to variable of type long long

I'm compiling the code below and for some reason I can't assign -2147483648 to the variable which is 8 bytes ... please shed some light on this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Parent directory of a file

Is there any way to find out the parent directory of a file using C program. I would like to give same ... the file. Any help is appreciated. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Truncating an int to char - is it defined?

unsigned char a, b; b = something(); a = ~b; A static analyzer complained of truncation in the last line, ... this warning in the first place. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Magic 7F45 error when running NDK executable on android

I created a simple Hello World C program, compiled it using ndk-build, and transferred it via adb. Essentially I ... . Please help. Thank you. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Struct packing and alignment with mingw

I am emulating code from an embedded system (stm32, Keil μVision 5, MDK-ARM) on a PC (mingw32, 32bit arch ... How can I correct this behaviour? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How to properly inline and use an inline function in C99, correcting link failure?

Doing cc -std=c99 example.c on the following simplified example.c file: inline void a() { } int main() { a() ... told so, but I have my reasons) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - passing argument makes pointer from integer

I can't find my problem. keeps giving me these errors: "c:2:5: note: expected 'int *' but argument is of ... even_count); 47 . return 0; 48 } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What does sizeof (function(argument)) return?

What will be the output of program #include <stdio.h> int fun(char *a){ printf("%d ",sizeof(a)); return 1; } ... sizeof (fun(a))); return 0; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What are the reasons to use "syscall" instead of calling the function directly?

There's syscall which allows indirect system calls in Linux. What are the reasons to use it - and why is ... than direct call to the function? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - initializing static variable with a function call gives compilation error?

#include <stdio.h> int foo(){ return 1; } int main(void) { static int q = foo(); return 0; } ... thread with similar query or a good answer. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How to allocate an executable page in a Linux kernel module?

I'm writing a Linux kernel module, and I'd like to allocate an executable page. Plain kmalloc() returns a pointer ... 2.6.31-20-generic-pae. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Address of dereferenced pointer construct

In unqlite c library I found following code: pObj = jx9VmReserveMemObj(&(*pVm),&nIdx); where pVm is: typedef ... (*pVm) equivalent to pVm? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Read nanosecond pcap file using libpcap

I have a nanosecond libpcap (nanosec.pcap) file and the nanosecond timestamp (eg 2.123456789) can be displayed by ... (ts), truncated_hdr); } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - OK to copy a CRITICAL_SECTION?

One can use a CRITICAL_SECTION variable to get mutual exclusion. My question is: does CRITICAL_SECTION support ... in the documentation. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Is it well-defined behavior to modify one element of an array while another thread modifies another element of the same array?

Given an array of type foo_t[n] and a set of n threads, where each of the n threads reads and modifies a ... foo_t is / what alignment it has? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What's the difference between alloca(n) and char x[n]?

What is the difference between void *bytes = alloca(size); and char bytes[size]; //Or to be more precise, ... value is unknown at compile-time. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Valgrind does not show line-numbers

I'm trying to find out where I made invalid writes to a piece of memory using Valgrind. It tells there is ... 0, size); return SPYR_NOERR; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - I used wait(&status) and the value of status is 256, why?

I have this line in my code : t = wait(&status); When the child process works, the value of status is 0, ... int status; t = wait(&status); See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why Could glGetString(GL_VERSION) Be Causing a Seg Fault?

I'm learning OpenGL on Fedora 13 and noticed that a call to glGetString is causing a seg fault. I've scraped Google, ... std::endl; return 0; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why is this inline assembly not working with a separate asm volatile statement for each instruction?

For the the following code: long buf[64]; register long rrax asm ("rax"); register long rrbx asm ("rbx"); ... properly, and how to solve it? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - what is the advantage of static function?

see in one project source code i have seen belows declaration static int *foo(); so it declare foo as ... of declaring function as static ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why is uint_least16_t faster than uint_fast16_t for multiplication in x86_64?

The C standard is quite unclear about the uint_fast*_t family of types. On a gcc-4.4.4 linux x86_64 system, the types ... ) to be a 4-byte type? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - get unsigned long long addition carry

I want to get the carry bit of adding two unsigned 64-bit integers in c. I can use x86-64 asm if needed. code: ... ", res, carry); return 0; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Win32, ReadFile from pipe block even after child terminated

I have a simple program (in C) that create two child process, wait on an inherited pipe each, and put the output ... if not, how to debug this)? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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