{"id":149818,"date":"2020-09-02T15:39:31","date_gmt":"2020-09-02T07:39:31","guid":{"rendered":"http:\/\/4563.org\/?p=149818"},"modified":"2020-09-02T15:39:31","modified_gmt":"2020-09-02T07:39:31","slug":"%e9%97%ae%e4%b8%80%e4%b8%aa-c-%e8%af%ad%e8%a8%80%e5%85%b3%e4%ba%8e%e6%96%87%e4%bb%b6%e6%93%8d%e4%bd%9c%e7%9a%84%e9%97%ae%e9%a2%98%ef%bc%8c%e5%a6%82%e4%bd%95%e5%b0%86-uint32_t-%e6%95%b0%e6%8d%ae","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=149818","title":{"rendered":"\u95ee\u4e00\u4e2a C \u8bed\u8a00\u5173\u4e8e\u6587\u4ef6\u64cd\u4f5c\u7684\u95ee\u9898\uff0c\u5982\u4f55\u5c06 uint32_t \u6570\u636e\u5199\u8fdb\u4e8c\u8fdb\u5236\u6587\u4ef6\uff0c 4byte \u5bf9\u9f50\uff1f"},"content":{"rendered":"
\n
\n
\n

\u95ee\u4e00\u4e2a C \u8bed\u8a00\u5173\u4e8e\u6587\u4ef6\u64cd\u4f5c\u7684\u95ee\u9898\uff0c\u5982\u4f55\u5c06 uint32_t \u6570\u636e\u5199\u8fdb\u4e8c\u8fdb\u5236\u6587\u4ef6\uff0c 4byte \u5bf9\u9f50\uff1f <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : ReputationZh <\/span> <\/i> 10<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
fwrite \u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f char \u7c7b\u578b\uff0c\u597d\u50cf\u4e0d\u652f\u6301\u554a\uff1f\u5e94\u8be5\u7528\u4ec0\u4e48\u65b9\u6cd5\u5199\u5165\u3002 <\/div>\n
\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (21<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : dangyuluo <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5728\u4e0d\u8003\u8651\u5b57\u8282\u5e8f\u7684\u60c5\u51b5\u4e0b\uff0c\u76f2\u731c\u6bcf\u6b21\u8bfb 8bit \u518d\u5199\u5165\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : louettagfh <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    1. open \u7684\u65f6\u5019\u52a0\u53c2\u6570 binary
    2. \u5199\u5bf9\u9f50\u6ca1\u6709\u610f\u4e49 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : zwy100e72 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u7b2c\u4e00\u4e2a\u4e0d\u662f char \u7c7b\u578b\uff0c\u800c\u662f\u6307\u5411 buffer \u7684\u4e00\u4e2a\u6307\u9488\uff1b\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f buffer \u7684\u957f\u5ea6\uff0c\u56e0\u6b64\u8981\u8fbe\u5230\u5199 4 bytes (sizeof(uint32_t))\u7684\u6548\u679c\uff0c\u4f60\u9700\u8981 ( https:\/\/godbolt.org\/z\/zMMWb3 ): <\/p>\n

    “`c
    #include <cstdint>
    #include <cstdio><\/p>\n

    void f(uint32_t i) {
    FILE* fp = fopen(“path\/to\/file.bin”, “wb”);
    fwrite(&i, sizeof(i), 1, fp);
    fclose(fp);
    }
    “`<\/p>\n

    https:\/\/en.cppreference.com\/w\/c\/io\/fwrite <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : XiaoxiaoPu <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u9700\u8981\u5148\u628a uint32_t \u8f6c\u5316\u6210 4 \u4e2a char\uff0c\u8fd9\u91cc\u6d89\u53ca\u5927\u5c0f\u7aef\u7684\u95ee\u9898\uff0c\u53ef\u4ee5\u641c\u4e00\u4e0b\u300c\u5927\u5c0f\u7aef\u300d <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : zwy100e72 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5bf9\u9f50\u4e0e\u5426\u4e4b\u524d\u53ea\u6709\u5728\u5185\u5b58\u4e2d\u624d\u6709\u5fc5\u8981\u5bf9\u9f50\uff0c\u66f4\u4f55\u51b5\u73b0\u5728\u4e0d\u5bf9\u9f50\u7684\u5185\u5b58\u8bbf\u95ee\u4e5f\u5df2\u7ecf\u5f88\u5feb\u4e86\uff0c\u4f60\u6ca1\u6709\u5fc5\u8981\u5bf9\u9f50 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : baoshuo <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5bf9\u9f50\u611f\u89c9\u6ca1\u7528 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : Tony042 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4e0d\u77e5\u9053 C \u600e\u4e48\u505a\uff0cC++\u5185\u7f6e\u4e86\u5173\u952e\u5b57 \u76f4\u63a5 alignas(4) uint_32 \u5373\u53ef <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : laminux29 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    C \u8bed\u8a00\u5c42\u6b21\uff0c\u6211\u4e0d\u5efa\u8bae\u4f60\u53bb\u4e3b\u52a8\u5bf9\u9f50\uff0c\u56e0\u4e3a\u8fd9\u4e2a\u5c42\u6b21\u7684\u6587\u4ef6\u8bfb\u5199\uff0c\u672c\u8d28\u662f\u628a buffer \u4ea4\u7ed9 OS \u53bb\u5904\u7406\u7684\uff0c\u6700\u540e\u8fd9\u4e9b buffer data \u5199\u5230\u5b58\u50a8\u8bbe\u5907\u65f6\uff0c\u662f\u5426\u8fdb\u884c\u5bf9\u9f50 io\uff0c\u662f\u7531 OS \u6765\u51b3\u5b9a\u7684\u3002<\/p>\n

    OS \u5728\u628a\u6570\u636e flush \u5230\u5b58\u50a8\u8bbe\u5907\u4e0a\u7684\u4f18\u5316\u52a8\u4f5c\uff0c\u53ef\u4e0d\u6b62\u5bf9\u9f50\u4e00\u79cd\u3002 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : yngzij <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6211\u8bb0\u5f97\u53ea\u6709\u5728 malloc \u7684\u65f6\u5019\u5bf9\u9f50\u5427 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : chinuno <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    (char*)&num \u76f4\u63a5\u8f6c\u6210 char \u7c7b\u578b\u6570\u7ec4\u5199\u5165 4 \u4e2a\u5b57\u8282\u5c31\u884c\u3002\u672c\u8eab uint32_t \u5c31\u662f 4 \u4e2a\u5b57\u8282\u4e5f\u4e0d\u7528\u8003\u8651\u5bf9\u9f50\u95ee\u9898\u5427\u3002\u8bfb\u7684\u65f6\u5019\u56db\u4e2a\u56db\u4e2a\u8bfb\u628a char \u6570\u7ec4\u8f6c\u56de uint32_t \u4e5f\u4e0d\u7528\u8003\u8651\u5b57\u8282\u5e8f\u7684\u95ee\u9898\u4e86 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : shuax <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    uint32_t \u4e0d\u5c31\u662f 4 \u4e2a\u5b57\u8282\uff0c\u8fd8\u5bf9\u9f50\u4ec0\u4e48 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : heguangyu5 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    mmap \u8981\u5199\u5165\u7684\u6587\u4ef6,\u7136\u540e align \u8981\u5199\u5165\u7684\u5730\u5740,\u7136\u540e memcpy.<\/p>\n

    \u7c7b\u4f3c\u8fd9\u6837:<\/p>\n

    fd = open()
    addr = mmap()
    ptr = addr + offset
    ptr = align()
    memcpy(ptr, &int_var, sizeof(int)) <\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : yolee599 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u8981\u8003\u8651\u5927\u7aef\u8fd8\u662f\u5c0f\u7aef\u50a8\u5b58 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : May725 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4ee5 binary \u5f62\u5f0f\u6253\u5f00\u6587\u4ef6\uff0c\u5199\u591a\u5c11\u4e2a\u5b57\u8282\u5c31\u662f\u591a\u5c11\u4e2a\u5b57\u8282 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : Chenamy2017 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u770b#3\uff0c\u600e\u4e48\u5199\u8fdb\u53bb\u5c06\u6765\u7528\u7684\u65f6\u5019\u600e\u4e48\u8bfb\u51fa\u6765\u5c31\u884c\u4e86\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : CRVV <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);<\/p>\n

    fwrite \u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\u660e\u660e\u662f const void* \u7c7b\u578b<\/p>\n

    \u76f4\u63a5
    uint32_t x;
    fwrite(&x, 4, …)
    \u5e94\u8be5\u5c31\u80fd\u7528<\/p>\n

    \u53e6\u5916\uff0c\u6ca1\u6709\u7406\u89e3\u4e3b\u8bf4\u7684 \u5bf9\u9f50 \u662f\u6307\u4ec0\u4e48\uff0c\u5982\u679c\u4ece\u5934\u5f00\u59cb\u5199\uff0c\u6bcf\u6b21\u5199 4 bytes\uff0c\u90a3\u5f53\u7136\u662f\u5bf9\u9f50\u5230 4 bytes \u4e0a\u7684 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : wizardoz <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6211\u611f\u89c9\u76f4\u63a5\u5199\u5c31\u662f\u5bf9\u9f50\u7684\uff0c\u4e3a\u6b64\u6211\u8fd8\u7279\u610f\u5199\u4ee3\u7801\u6d4b\u8bd5\u4e86\u4e00\u4e0b\uff1a
    #include <stdio.h><\/p>\n

    typedef struct {
    char a;
    int b;
    char c;
    } Test_t;<\/p>\n

    int main(int argc, char* argv[]) {
    Test_t test = {
    .a = 1,
    .b = 2,
    .c = 3
    };<\/p>\n

    FILE *fp = fopen(“\/tmp\/data.bin”, “wb”);
    if (fp != NULL) {
    fwrite(&test, sizeof(test), 1, fp);<\/p>\n

    fclose(fp);
    }
    return 0;
    }<\/p>\n

    \u6587\u4ef6\u5185\u5bb9\uff1a
    00000000: 0156 0000 0200 0000 037f 0000 0a .V……….. <\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : wizardoz <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4f60\u5199\u5230\u6587\u4ef6\u662f\u51e0\u5b57\u8282\u5bf9\u9f50\u5e94\u8be5\u662f\u4e0e\u4f60\u7684\u6570\u636e\u5728\u5185\u5b58\u4e2d\u662f\u51e0\u5b57\u8282\u5bf9\u9f50\u4e00\u81f4\u7684\uff0c\u6bd5\u7adf\u5199\u7684\u65f6\u5019\u53ea\u662f\u628a\u5185\u5b58\u539f\u6837\u5199\u8fdb\u53bb\u3002
    \u5982\u679c\u4f60\u8bbe\u7f6e\u4e86\u5185\u5b58 1 \u5b57\u8282\u5bf9\u9f50\uff0c\u90a3\u4e48\u5199\u5230\u6587\u4ef6\u4e5f\u662f 1 \u5b57\u8282\u5bf9\u9f50\u7684\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : CRVV <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @wizardoz <\/p>\n

    struct \u91cc\u9762\u7684 field \u90fd\u4f1a self-align\uff0c\u628a int b \u653e\u5230 char a \u524d\u9762\uff0cchar c \u5c31\u4e0d\u4f1a align \u5230 4 bytes \u4e0a\u4e86\u3002 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : ReputationZh <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @zwy100e72 \u611f\u8c22\u5927\u4f6c\uff0c\u4e0d\u8fc7\u6211\u6709\u4e2a\u7591\u95ee\uff0c\u5047\u8bbe\u6211\u7684\u6570\u636e\u7c7b\u578b\u662f uint32_t\uff0c\u4f46\u662f\u6211 fwrite \u7684\u65f6\u5019\u5927\u5c0f\u586b\u5199\u7684 5 \u6216\u8005 8 \uff08\u4e0d\u4e3a uint32_t \u7684 4 \uff09\uff0c\u6211\u5199\u8fdb\u53bb\u7684\u6570\u636e\u662f\u771f\u5b9e\u7684\u5417\uff1f\u591a\u4f59\u7684\u5b57\u8282\u6570\u4f1a\u4ea7\u751f\u4ec0\u4e48\u5f02\u53d8\u5417\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : ReputationZh <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @wizardoz \u7406\u89e3\u4e86\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"

    \u95ee\u4e00\u4e2a C \u8bed\u8a00\u5173\u4e8e\u6587\u4ef6\u64cd\u4f5c\u7684\u95ee\u9898…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/149818"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=149818"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/149818\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=149818"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=149818"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=149818"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}