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C語言:深複製VS淺複製 陣列VS指標

計算機是32位的,編譯器是dev-cpp。

C原始碼:

#include <stdio.h>

struct student{
       char *name1;
       char name2[20];
}stu;

int main()
{
    struct student *p;
    p = &stu;
    //strcpy((*p).name1,"first");// 編譯正確,執行錯誤,因為沒有分配空間。
    strcpy((*p).name2,"second");  // 深複製:複製陣列所有的字元 
    printf("name1 = %s \t name2 = %s\n",(*p).name1,(*p).name2);
    
    p->name1 = "third";   // 淺複製,只複製記憶體地址 
    printf("name1 = %s \t name2 = %s\n",(*p).name1,(*p).name2);
    //p->name2 = "fourth";  //編譯錯誤: incompatible types in assignment of `const char[7]' to `char[20]' 
    char tp[20]="fifth";  
    //p->name2 = tp;  //編譯錯誤:ISO C++ forbids assignment of arrays 
    // 深複製和淺複製的區別 
    strcpy((*p).name2,tp);
    p->name1 = tp;
    tp[0]='F';//修改tp字串的值
    printf("name1 = %s \t name2 = %s\n",(*p).name1,(*p).name2); // 淺複製的值發生改變,深複製不會
    
    // 字串陣列和指標的區別
    printf("sizeof(char *name) = %d\nsizeof(char name[20]) = %d\n", sizeof(p->name1), sizeof(p->name2)); // 32位計算機4和20 
    system("PAUSE");
    return 0;
}

執行結果為:

name1 = (null)   name2 = second
name1 = third    name2 = second
name1 = Fifth    name2 = fifth
sizeof(char *name) = 4
sizeof(char name[20]) = 20