{"id":3404,"date":"2025-04-01T23:21:31","date_gmt":"2025-04-01T15:21:31","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=3404"},"modified":"2025-04-01T23:21:31","modified_gmt":"2025-04-01T15:21:31","slug":"c-%e8%af%ad%e8%a8%80-%e6%8c%87%e9%92%88%ef%bc%88pointer%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/04\/01\/c-%e8%af%ad%e8%a8%80-%e6%8c%87%e9%92%88%ef%bc%88pointer%ef%bc%89\/","title":{"rendered":"C \u8bed\u8a00 \u6307\u9488\uff08Pointer\uff09"},"content":{"rendered":"\n<p>C \u8bed\u8a00\u4e2d\u7684 <strong>\u6307\u9488<\/strong>\uff08Pointer\uff09\u662f\u5176\u6700\u5f3a\u5927\u7684\u7279\u6027\u4e4b\u4e00\uff0c\u5b83\u5141\u8bb8\u7a0b\u5e8f\u76f4\u63a5\u64cd\u4f5c\u5185\u5b58\uff0c\u63d0\u9ad8\u4ee3\u7801\u7684\u6548\u7387\u548c\u7075\u6d3b\u6027\u3002\u6307\u9488\u5e7f\u6cdb\u7528\u4e8e\u52a8\u6001\u5185\u5b58\u5206\u914d\u3001\u6570\u636e\u7ed3\u6784\uff08\u5982\u94fe\u8868\u3001\u6811\uff09\u3001\u6570\u7ec4\u64cd\u4f5c\u3001\u51fd\u6570\u53c2\u6570\u4f20\u9012\u7b49\u3002\u672c\u6587\u5c06\u4ece\u57fa\u7840\u5230\u9ad8\u7ea7\u5168\u9762\u89e3\u6790 C \u6307\u9488\uff0c\u5305\u62ec\u5e95\u5c42\u539f\u7406\u3001\u4f7f\u7528\u6280\u5de7\u548c\u6ce8\u610f\u4e8b\u9879\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>1. \u6307\u9488\u7684\u57fa\u672c\u6982\u5ff5<\/strong><\/h2>\n\n\n\n<p>\u5728 C \u8bed\u8a00\u4e2d\uff0c\u6307\u9488\u662f\u4e00\u4e2a <strong>\u53d8\u91cf<\/strong>\uff0c\u5b83\u5b58\u50a8 <strong>\u53e6\u4e00\u4e2a\u53d8\u91cf\u7684\u5185\u5b58\u5730\u5740<\/strong>\u3002\u6307\u9488\u672c\u8eab\u4e5f\u5360\u7528\u5185\u5b58\uff08\u901a\u5e38\u4e3a 4 \u6216 8 \u5b57\u8282\uff0c\u53d6\u51b3\u4e8e\u7cfb\u7edf\u67b6\u6784\uff09\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>1.1 \u6307\u9488\u7684\u5b9a\u4e49<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int a = 10;\nint *p = &amp;a;  \/\/ p \u5b58\u50a8\u53d8\u91cf a \u7684\u5730\u5740<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>*p<\/code> \u8868\u793a <strong>\u6307\u9488\u89e3\u5f15\u7528<\/strong>\uff08dereferencing\uff09\uff0c\u5373\u8bbf\u95ee\u6307\u9488\u6307\u5411\u7684\u503c\u3002<\/li>\n\n\n\n<li><code>&amp;a<\/code> \u53d6 <code>a<\/code> \u7684\u5730\u5740\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>1.2 \u6307\u9488\u7684\u57fa\u672c\u64cd\u4f5c<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>#include &lt;stdio.h>\n\nint main() {\n    int a = 10;\n    int *p = &amp;a;\n\n    printf(\"\u53d8\u91cf a \u7684\u503c: %d\\n\", a);\n    printf(\"\u53d8\u91cf a \u7684\u5730\u5740: %p\\n\", &amp;a);\n    printf(\"\u6307\u9488 p \u5b58\u50a8\u7684\u5730\u5740: %p\\n\", p);\n    printf(\"\u6307\u9488 p \u6307\u5411\u7684\u503c: %d\\n\", *p);\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>\u793a\u4f8b\u8f93\u51fa<\/strong><\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>\u53d8\u91cf a \u7684\u503c: 10\n\u53d8\u91cf a \u7684\u5730\u5740: 0x7ffee1b56c44\n\u6307\u9488 p \u5b58\u50a8\u7684\u5730\u5740: 0x7ffee1b56c44\n\u6307\u9488 p \u6307\u5411\u7684\u503c: 10<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>2. \u6307\u9488\u7684\u7c7b\u578b<\/strong><\/h2>\n\n\n\n<p>\u6307\u9488\u7684\u7c7b\u578b\u51b3\u5b9a\u4e86\u89e3\u5f15\u7528\uff08<code>*<\/code>\uff09\u65f6\u8bfb\u53d6\u6570\u636e\u7684\u65b9\u5f0f\u3002\u4f8b\u5982\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>int *p1;   \/\/ \u6307\u5411 int \u7c7b\u578b\nchar *p2;  \/\/ \u6307\u5411 char \u7c7b\u578b\ndouble *p3; \/\/ \u6307\u5411 double \u7c7b\u578b<\/code><\/pre>\n\n\n\n<p><strong>\u6ce8\u610f\uff1a<\/strong> \u6307\u9488\u672c\u8eab\u7684\u5927\u5c0f\u901a\u5e38\u662f\u56fa\u5b9a\u7684\uff0832 \u4f4d\u7cfb\u7edf 4 \u5b57\u8282\uff0c64 \u4f4d\u7cfb\u7edf 8 \u5b57\u8282\uff09\uff0c\u4f46\u6307\u5411\u7684\u6570\u636e\u7c7b\u578b\u4e0d\u540c\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>3. \u6307\u9488\u8fd0\u7b97<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>3.1 \u6307\u9488\u52a0\u51cf<\/strong><\/h3>\n\n\n\n<p>\u6307\u9488\u53ef\u4ee5\u6267\u884c\u52a0\u6cd5\u548c\u51cf\u6cd5\u8fd0\u7b97\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>int arr&#91;] = {10, 20, 30, 40};\nint *p = arr; \/\/ \u6307\u5411\u6570\u7ec4\u9996\u5143\u7d20\n\nprintf(\"%d\\n\", *(p + 1)); \/\/ \u8bbf\u95ee arr&#91;1] (20)\nprintf(\"%d\\n\", *(p + 2)); \/\/ \u8bbf\u95ee arr&#91;2] (30)<\/code><\/pre>\n\n\n\n<p><strong>\u539f\u7406<\/strong>\uff1a<br>\u6307\u9488 <code>p<\/code> \u589e\u52a0 <code>1<\/code>\uff0c\u8868\u793a\u524d\u8fdb <code>sizeof(int)<\/code>\uff084 \u5b57\u8282\uff09\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>3.2 \u6307\u9488\u7684\u6bd4\u8f83<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>if (p1 == p2) {\n    printf(\"\u4e24\u4e2a\u6307\u9488\u6307\u5411\u76f8\u540c\u5730\u5740\\n\");\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>3.3 \u6307\u9488\u7684\u81ea\u589e\u3001\u81ea\u51cf<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>p++; \/\/ \u79fb\u52a8\u5230\u4e0b\u4e00\u4e2a\u5143\u7d20\np--; \/\/ \u79fb\u52a8\u5230\u4e0a\u4e00\u4e2a\u5143\u7d20<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>4. \u6307\u9488\u4e0e\u6570\u7ec4<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>4.1 \u4e00\u7ef4\u6570\u7ec4\u4e0e\u6307\u9488<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int arr&#91;] = {1, 2, 3, 4};\nint *p = arr;\n\nprintf(\"%d\\n\", p&#91;2]); \/\/ \u7b49\u4ef7\u4e8e arr&#91;2]\uff0c\u8f93\u51fa 3<\/code><\/pre>\n\n\n\n<p><code>arr[i]<\/code> \u7b49\u4ef7\u4e8e <code>*(arr + i)<\/code>\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>4.2 \u4e8c\u7ef4\u6570\u7ec4\u4e0e\u6307\u9488<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int matrix&#91;2]&#91;3] = {{1, 2, 3}, {4, 5, 6}};\nint (*p)&#91;3] = matrix; \/\/ \u6307\u5411\u5305\u542b 3 \u4e2a\u5143\u7d20\u7684\u6570\u7ec4\nprintf(\"%d\\n\", p&#91;1]&#91;2]); \/\/ \u8bbf\u95ee matrix&#91;1]&#91;2]\uff0c\u8f93\u51fa 6<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>5. \u6307\u9488\u4e0e\u51fd\u6570<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>5.1 \u4f5c\u4e3a\u51fd\u6570\u53c2\u6570<\/strong><\/h3>\n\n\n\n<p>\u6307\u9488\u53ef\u4ee5\u7528\u4e8e\u51fd\u6570\u53c2\u6570\uff0c\u4ee5\u4fbf <strong>\u4fee\u6539\u539f\u59cb\u6570\u636e<\/strong>\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>void modify(int *p) {\n    *p = 20; \/\/ \u4fee\u6539\u539f\u59cb\u503c\n}\n\nint main() {\n    int a = 10;\n    modify(&amp;a);\n    printf(\"%d\\n\", a); \/\/ \u8f93\u51fa 20\n    return 0;\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>5.2 \u8fd4\u56de\u6307\u9488<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int* getPointer() {\n    static int x = 100;\n    return &amp;x;\n}<\/code><\/pre>\n\n\n\n<p>\u26a0\ufe0f <strong>\u6ce8\u610f<\/strong>\uff1a\u4e0d\u8981\u8fd4\u56de\u5c40\u90e8\u53d8\u91cf\u7684\u5730\u5740\uff0c\u5426\u5219\u4f1a\u5bfc\u81f4\u672a\u5b9a\u4e49\u884c\u4e3a\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>6. \u6307\u9488\u4e0e <code>malloc()<\/code> \u52a8\u6001\u5185\u5b58\u5206\u914d<\/strong><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n\nint main() {\n    int *p = (int*) malloc(5 * sizeof(int)); \/\/ \u5206\u914d 5 \u4e2a int \u7a7a\u95f4\n    if (p == NULL) {\n        printf(\"\u5185\u5b58\u5206\u914d\u5931\u8d25\\n\");\n        return 1;\n    }\n\n    for (int i = 0; i &lt; 5; i++) {\n        p&#91;i] = i * 10;\n        printf(\"%d \", p&#91;i]);\n    }\n\n    free(p); \/\/ \u91ca\u653e\u5185\u5b58\n    return 0;\n}<\/code><\/pre>\n\n\n\n<p>\u26a0\ufe0f <strong>\u6ce8\u610f<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u5206\u914d\u540e\u5fc5\u987b\u91ca\u653e <code>free(p)<\/code><\/strong>\uff0c\u5426\u5219\u53ef\u80fd\u4f1a\u9020\u6210 <strong>\u5185\u5b58\u6cc4\u6f0f<\/strong>\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>7. \u6307\u9488\u6570\u7ec4 &amp; \u6307\u9488\u6307\u9488<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>7.1 \u6307\u9488\u6570\u7ec4<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int a = 1, b = 2, c = 3;\nint *arr&#91;] = {&amp;a, &amp;b, &amp;c};\n\nprintf(\"%d\\n\", *arr&#91;1]); \/\/ \u8f93\u51fa 2<\/code><\/pre>\n\n\n\n<p>\u6307\u9488\u6570\u7ec4 <code>arr[]<\/code> \u91cc\u5b58\u50a8\u4e86 <code>a, b, c<\/code> \u7684\u5730\u5740\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>7.2 \u4e8c\u7ea7\u6307\u9488\uff08\u6307\u5411\u6307\u9488\u7684\u6307\u9488\uff09<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int x = 10;\nint *p = &amp;x;\nint **pp = &amp;p;\n\nprintf(\"%d\\n\", **pp); \/\/ \u8f93\u51fa 10<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>8. <code>void *<\/code> \u6307\u9488<\/strong><\/h2>\n\n\n\n<p><code>void *<\/code> \u6307\u9488\u53ef\u4ee5\u6307\u5411\u4efb\u4f55\u7c7b\u578b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>void *ptr;\nint a = 10;\nptr = &amp;a;\nprintf(\"%d\\n\", *(int*)ptr);<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>9. \u6307\u9488\u7684\u5e38\u89c1\u9519\u8bef<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>9.1 \u60ac\u7a7a\u6307\u9488\uff08Dangling Pointer\uff09<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int *p;\n{\n    int x = 10;\n    p = &amp;x;\n} \/\/ x \u88ab\u9500\u6bc1\uff0cp \u6210\u4e3a\u60ac\u7a7a\u6307\u9488<\/code><\/pre>\n\n\n\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong> <strong>\u907f\u514d\u8fd4\u56de\u5c40\u90e8\u53d8\u91cf\u5730\u5740<\/strong>\uff0c\u6216\u8005\u5728 <code>free()<\/code> \u540e\u5c06\u6307\u9488\u7f6e <code>NULL<\/code>\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>9.2 \u91ce\u6307\u9488\uff08Uninitialized Pointer\uff09<\/strong><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>int *p; \/\/ p \u672a\u521d\u59cb\u5316\uff0c\u53ef\u80fd\u6307\u5411\u5783\u573e\u5730\u5740<\/code><\/pre>\n\n\n\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong> \u5728\u58f0\u660e\u6307\u9488\u65f6\u521d\u59cb\u5316\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>int *p = NULL;<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>10. \u603b\u7ed3<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u6307\u9488\u7279\u6027<\/th><th>\u8bf4\u660e<\/th><\/tr><\/thead><tbody><tr><td>\u5b58\u50a8\u5730\u5740<\/td><td>\u6307\u9488\u5b58\u50a8\u53d8\u91cf\u7684\u5730\u5740\uff0c\u800c\u975e\u53d8\u91cf\u672c\u8eab<\/td><\/tr><tr><td><code>*<\/code> \u89e3\u5f15\u7528<\/td><td>\u8bbf\u95ee\u6307\u9488\u6307\u5411\u7684\u6570\u636e<\/td><\/tr><tr><td><code>&amp;<\/code> \u53d6\u5730\u5740<\/td><td>\u83b7\u53d6\u53d8\u91cf\u5730\u5740<\/td><\/tr><tr><td>\u6307\u9488\u8fd0\u7b97<\/td><td>\u652f\u6301 <code>+<\/code>, <code>-<\/code>, <code>++<\/code>, <code>--<\/code><\/td><\/tr><tr><td><code>malloc\/free<\/code><\/td><td><strong>\u52a8\u6001\u5185\u5b58\u5206\u914d<\/strong><\/td><\/tr><tr><td><code>void *<\/code><\/td><td>\u901a\u7528\u6307\u9488\uff0c\u6307\u5411\u4efb\u610f\u7c7b\u578b<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>11. \u53c2\u8003\u8d44\u6599<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.open-std.org\/jtc1\/sc22\/wg14\/www\/docs\/n2310.pdf\">ISO C \u6807\u51c6 (C18) &#8211; Pointer Types<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/gcc.gnu.org\/onlinedocs\/gcc\/Pointer-Types.html\">GCC Pointer \u6587\u6863<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>C \u8bed\u8a00\u4e2d\u7684 \u6307\u9488\uff08Pointer\uff09\u662f\u5176\u6700\u5f3a\u5927\u7684\u7279\u6027\u4e4b\u4e00\uff0c\u5b83\u5141\u8bb8\u7a0b\u5e8f\u76f4\u63a5\u64cd\u4f5c\u5185\u5b58\uff0c\u63d0\u9ad8\u4ee3\u7801\u7684\u6548\u7387\u548c\u7075\u6d3b\u6027\u3002\u6307\u9488 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3405,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[82],"tags":[],"class_list":["post-3404","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-c"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3404","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=3404"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3404\/revisions"}],"predecessor-version":[{"id":3406,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3404\/revisions\/3406"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media\/3405"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=3404"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=3404"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=3404"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}