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初始化对象时,0是什么意思?

c c++

247

Mahmoud Al-Qudsi · 技术社区 · 16 年前

什么时候? {0} 用于初始化对象,这意味着什么?我找不到任何关于 { 0 } 任何地方,而且由于大括号的缘故,谷歌搜索没有帮助。

示例代码:

SHELLEXECUTEINFO sexi = {0}; // what does this do?
sexi.cbSize = sizeof(SHELLEXECUTEINFO);
sexi.hwnd = NULL;
sexi.fMask = SEE_MASK_NOCLOSEPROCESS;
sexi.lpFile = lpFile.c_str();
sexi.lpParameters = args;
sexi.nShow = nShow;

if(ShellExecuteEx(&sexi))
{
    DWORD wait = WaitForSingleObject(sexi.hProcess, INFINITE);
    if(wait == WAIT_OBJECT_0)
        GetExitCodeProcess(sexi.hProcess, &returnCode);
}

如果没有它,上述代码将在运行时崩溃。

9 回复 | 直到 16 年前

296

Don Neufeld 9 年前

{0} 0

struct S { int a; char* b; int c; };
S ss = { 1, "asdf" };

ss.a 1 ss.b "asdf" ss.c int()

here

Harold Ekstrom 16 年前

struct foo
{
    char c;
    int  i;
};

foo a = {0};

foo a;
memset(&a,0,sizeof(a));

dalle 16 年前

SHELLEXECUTEINFO sexi = {};
char mytext[100] = {};

Ziezi sethi 9 年前

ShellExecuteEx() SHELLEXECUTEINFO

sexi.lpDirectory

SHELLEXECUTEINFO sexi = {0};

Adam Pierce 16 年前

char mytext[100] = {0};

Keith Thompson 10 年前

{0}

N1570 draft

0 0.0

{ }

int arr[2][2] = { { 1, 2 }, {3, 4} };

int arr[2][2] = { 1, 2, 3, 4 };

{ { 0 } }

some_type obj = { 0 };

obj

sexi.cbSize SHELLEXECUTEINFO { 0 }

memset

µBio 16 年前

Ingo Blackman 12 年前

struct foo bar = { 0 };

struct f {
    int x;
    char a;
} my_zero_struct;

int main(void)
{
    return my_zero_struct.x;
}

gcc -O2 -o check check.c readelf -s check | sort -k 2

59: 0000000000601018     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
48: 0000000000601018     0 NOTYPE  GLOBAL DEFAULT  ABS _edata
25: 0000000000601018     0 SECTION LOCAL  DEFAULT   25 
33: 0000000000601018     1 OBJECT  LOCAL  DEFAULT   25 completed.6531
34: 0000000000601020     8 OBJECT  LOCAL  DEFAULT   25 dtor_idx.6533
62: 0000000000601028     8 OBJECT  GLOBAL DEFAULT   25 my_zero_struct
57: 0000000000601030     0 NOTYPE  GLOBAL DEFAULT  ABS _end