{"id":248401,"date":"2021-01-01T00:16:34","date_gmt":"2020-12-31T16:16:34","guid":{"rendered":"http:\/\/4563.org\/?p=248401"},"modified":"2021-01-01T00:16:34","modified_gmt":"2020-12-31T16:16:34","slug":"%e8%af%b7%e6%95%99%e5%a4%a7%e5%ae%b6%e4%b8%80%e4%b8%aa-c-%e6%8c%87%e9%92%88%e7%9a%84%e9%97%ae%e9%a2%98","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=248401","title":{"rendered":"\u8bf7\u6559\u5927\u5bb6\u4e00\u4e2a C \u6307\u9488\u7684\u95ee\u9898"},"content":{"rendered":"
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\u8bf7\u6559\u5927\u5bb6\u4e00\u4e2a C \u6307\u9488\u7684\u95ee\u9898 <\/h1>\n

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\u8cc7\u6df1\u5927\u4f6c : GromHellscream <\/span> <\/i> 2<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n
#include <stdio.h> #include <stdlib.h>  int main(int argc, char *argv[]) {  int a[4] = {150, 250, 350, 450};  int * c = a;  printf(\"1: a[0] = %d, a[1] = %d, a[2] = %d, a[3] = %dn\", a[0], a[1], a[2], a[3]);  c = c + 1;  printf(\"current c points to %dn\", *c);    c = (int *) ((char *) c + 1);  *c = 500;    printf(\"2: a[0] = %d, a[1] = %d, a[2] = %d, a[3] = %dn\", a[0], a[1], a[2], a[3]); } <\/code><\/pre>\n
\u8f93\u51fa\uff1a
 1: a[0] = 150, a[1] = 250, a[2] = 350, a[3] = 450
 current c points to 250
 2: a[0] = 150, a[1] = 128250, a[2] = 256, a[3] = 450 <\/p>\n
\u8bf7\u6559\u4e0b\u5927\u5bb6\uff0c\u6700\u540e a[1] \u548c a[2] \u4e3a\u4ec0\u4e48\u5206\u522b\u53d8\u6210 128250 \u548c 256 \u4e86\uff1f
 \u6c42\u8d50\u6559\uff0c\u8c22\u8c22\uff01<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (9<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
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     \u8cc7\u6df1\u5927\u4f6c : qianlv7 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 c = (int *) ((char *) c + 1); int* \u505a\u8fd0\u7b97\u662f\u6309 4 \u4e2a\u5b57\u8282\u7684, char* \u6307\u9488\u7684\u8fd0\u7b97\u662f 1 \u4e2a\u5b57\u8282\u7684\uff0c \u6240\u4ee5\u8fd9\u53e5 c \u73b0\u5728\u7684\u4f4d\u7f6e\u5c31\u505a 1\uff0c2 \u4e4b\u95f4\u7684\u5185\u5b58\u4e86\uff0c\u7136\u540e*c = 500 \u5c31\u5bfc\u81f4 2 \u4e2a\u4f4d\u7f6e\u7684\u5185\u5b58\u90fd\u4fee\u6539\u4e86\u90e8\u5206                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : GromHellscream <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @qianlv7 \u597d\u7684\uff0c\u8c22\u8c22\u4f60\u3002\u90a3\u80fd\u7ed9\u51fa\u8fd9\u4e2a 128250 \u548c 256 \u7684\u8ba1\u7b97\u8fc7\u7a0b\u5417\uff1f\u5bfc\u81f4\u8fd9\u4e24\u4e2a\u503c\u7684\u539f\u56e0\u6211\u5927\u6982\u61c2\u4e86\uff0c\u4f46\u600e\u4e48\u7b97\u51fa\u6765\u7684\uff0c\u4e0d\u592a\u61c2\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : learningman <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6307\u9488+1 \u7684 1 \u6307\u7684\u662f\u6307\u9488\u5bf9\u5e94\u7684\u6570\u636e\u7ed3\u6784\u7684\u5355\u4f4d\u5185\u5b58\u5927\u5c0f\u5427\uff08\u4e0d\u786e\u5b9a\uff09                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : qianlv7 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @GromHellscream \u4f60\u5c31\u662f\u4fee\u6539\u4e86 a[1] \u7684\u540e 3 \u4e2a\u5b57\u8282\uff0c\u540e a[2] \u7684\u7b2c\u4e00\u4e2a\u5b57\u8282                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : Lime <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 “`c
    #include <stdio.h>
    #include <stdlib.h><\/p>\n
    int main(int argc, char *argv[]) {
     \/\/ \u770b\u8d77\u6765\u4f60\u662f\u5728 x86_64 \u4e0a\u6765\u8dd1\u7684, int \u4e3a 4-bytes, \u6b64\u65f6\u5185\u5b58\u5e03\u5c40\u4e3a:
     \/\/
     \/\/ a[0]
     \/\/ \u2193
     \/\/ 69000000 af000000 e5100000 2c100000
     int a[4] = {150, 250, 350, 450};<\/p>\n
     int * c = a;
     printf(“1: a[0] = %d, a[1] = %d, a[2] = %d, a[3] = %dn”, a[0], a[1], a[2], a[3]);<\/p>\n
     \/\/ c
     \/\/ \u2193
     \/\/ 69000000 af000000 e5100000 2c100000
     c = c + 1;
     printf(“current c points to %dn”, *c);<\/p>\n
     \/\/
     \/\/ c
     \/\/ \u2193
     \/\/ 69000000 af000000 e5100000 2c100000
     c = (int *) ((char *) c + 1);
     printf(“%pn”, c);<\/p>\n
     \/\/ c
     \/\/ \u2193
     \/\/ 69000000 af4f1000 00100000 2c100000
     \/\/
     \/\/ \u6700\u7ec8:
     \/\/
     \/\/ a[0] = 0x96
     \/\/ a[1] = 0x1f4fa -> 128250
     \/\/ a[2] = 0x100 -> 256
     \/\/ a[4] = 0x1c2
     *c = 500;<\/p>\n
     printf(“2: a[0] = %d, a[1] = %d, a[2] = %d, a[3] = %dn”, a[0], a[1], a[2], a[3]);
    }
    “`                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : Lime <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 v2ex \u7f16\u8f91\u56de\u590d\u771f\u662f\u86cb\u75bc<\/p>\n
    https:\/\/gist.github.com\/shiyanhui\/f22eb5295b48edb46b43dad1ebe54b03