陣列與字串、字元指標與其他型別指標、賦值引數、指標引數以及引用引數、函式指標
阿新 • • 發佈：2019-02-12
◆陣列和字串
從表面上看，一個字串就是一個字元陣列，但在C++語句中，兩者並不完全相同。
字串是一個以串尾符"\0"結尾的字元型陣列，但任一個字元型陣列不見得必為字串(因為其中可以不包含"\0"結尾字元)。
char string1[7]="China";char string2[]="China";
char string3[7]={'C','h','i','n','a'};char string4[7]={'C','h','i','n','a','\0'};
string1的長度為7，賦初值後其前6個元素已被賦值(第6個元素為'\0')；string2的長度為6(第6個元素為'\0')；
string3的長度為7，最後沒有串尾符'\0'；
string4的長度為7，賦初值後與string1相同。
◆字元指標與其他型別指標的使用區別
讀下列程式：
1
#include<iostream> 2usingnamespace std;3
int main()4
{5
char str[10]="abcdefghi";6
int a[10]={0,1,2,3,4,5,6,7,8,9};7
cout<<"'cout<<str'=>"<<str<<endl;8
cout<<"'cout<<a'=>"<<a<<endl;9
cout<<"--------------------"<<10
cout<<"'cout<<&str'=>"<<&str<<endl;11
cout<<"'cout<<&a'=>"<<&a<<endl;12
cout<<"--------------------"<<endl;13
cout<<"'cout<<(int*)str'=>"<<(int*)str<<endl;14
cout<<15
cout<<"--------------------"<<endl;16
cout<<"'cout<<str+1'=>"<<str+1<<endl;17
cout<<"'cout<<a+1'=>"<<a+1<<endl;18
cout<<"--------------------"<<endl;19
cout<<"'cout<<&str[1]'=>"<<&str[1]<<endl;20
cout<<"'cout<<&a[1]'=>"<<&a[1]<<endl;21
cout<<"--------------------"<<endl;22
cout<<"'cout<<(int*)(str+1)'=>"<<(int*)(str+1)<<endl;23
cout<<"'cout<<(double*)(a+1)'=>"<<(double*)(a+1)<<endl;24
cout<<"--------------------"<<endl;25
cout<<"'cout<<(double*)(&str[1])'=>"<<(double*)(&str[1])<<endl;26
cout<<"'cout<<(double*)(&a[1])'=>"<<(double*)(&a[1])<<endl;27
cout<<"--------------------"<<endl;28
return0;29
}30
輸出結果：1
'cout<<str'=>abcdefghi2
'cout<<a'=>0X0065FDC4//存放地址，可以不同(下同) 3-------------------------- 4'cout<<&str'=>0X0065FDEC 5'cout<<&a'=>0X0065FDC4 6-------------------------- 7'cout<<(int*)str'=>0X0065FDEC 8'cout<<(double*)a'=>0X0065FDC4 9--------------------------10'cout<<str+1'=>bcdefghi11
'cout<<a+1'=>0X0065FDC812--------------------------13'cout<<&str[1]'=>bcdefghi14
'cout<<&a[1]'=>0X0065FDC815--------------------------16'cout<<(int*)(str+1)'=>0X0065FDED17'cout<<(double*)(a+1)'=>0X0065FDC818--------------------------19'cout<<(double*)(&str[1])'=>0X0065FDED20'cout<<(double*)(&a[1])'=>0X0065FDC821--------------------------
分析：字元指標與其他型別的指標(如int型指標)在使用上是有所區別的(字元指標具有其特殊性)。如，輸出字元陣列名即字元指標
，就是輸出字元指標所指向的那一個字串；而輸出int型陣列名即int型指標，就是輸出當前的指標值(一個地址)。但輸出
字元陣列名取地址，或輸出int型陣列名取地址，都可以輸出當前的指標值(一個地址)。另外，若將字元陣列名即字元指標
的型別進行轉換後，輸出的將是當前的指標值(一個地址)。
◆賦值引數、指標引數以及引用引數的使用區別
讀下面程式：
1
#include<iostream> 2usingnamespace std;3
int myFunc(int i1,int* pi21,int*& pi22,int& ri3,char* str);4
5
int main()6
{7
int i=1,a[2]={21,202},*pa=a,b[2]={21,202},*pb=b,r=3456;8
char s[]="ABCDEFG";9
cout<<"--------In main position 1--------"<<endl;10
cout<<"i,*pa,*pb,r,s="<<i<<","<<*pa<<","<<*pb<<","11 <<r<<","<<s<<endl;12
cout<<"a[0],a[1],b[0],b[1]="<<a[0]<<","<<a[1]<<","13 <<b[0]<<","<<b[1]<<endl;14
int tmp=myFunc(i,pa,pb,r,s);15
cout<<"--------In main position2 2--------"<<endl;16
cout<<"i,*pa,*pb,r,s="<<i<<","<<*pa<<","<<*pb<<","17 <<r<<","<<s<<endl;18
cout<<"a[0],a[1],b[0],b[1]="<<a[0]<<","<<a[1]<<","19 <<b[0]<<","<<b[1]<<endl;20
cout<<"tmp="<<tmp<<endl;21
return0;22
}23int myFunc(int i1,int* pi21,int*& pi22,int& ri3,char* str)24
{25
cout<<"--------In myFunc position 1-------"<<endl;26
cout<<"i1,*pi21,*pi22,ri3,str="<<i1<<","<<*pi21<<","27 <<*pi22<<","<<ri3<<","<<str<<endl;28
i1++;29
pi21++;30
pi22++;31
ri3++;32
(*str)++;33
cout<<"--------In myFunc position 2-------"<<endl;34
cout<<"i1,*pi21,*pi22,ri3,str="<<i1<<","<<*pi21<<","35 <<*pi22<<","<<ri3<<","<<str<<endl;36
i1++;37
(*pi21)++;38
(*pi22)++;39
ri3++;40
str++;41
cout<<"--------In myFunc position 3-------"<<endl;42
cout<<"i1,*pi21,*pi22,ri3,str="<<i1<<","<<*pi21<<","43 <<*pi22<<","<<ri3<<","<<str<<endl;44
45
return i1;46
}47
執行結果為：--------In main position 1--------i,*pa,*pb,r,s=1,21,21,3456,ABCDEFGa[0],a[1],b[0],b[1]=21,202,21,202--------In myFunc position 1-------i1,*pi21,*pi22,ri3,str=1,21,21,3456,ABCDEFG--------In myFunc position 2-------i1,*pi21,*pi22,ri3,str=2,202,202,3457,BBCDEFG--------In myFunc position 3-------i1,*pi21,*pi22,ri3,str=3,203,203,3458,BCDEFG--------In main position2 2--------i,*pa,*pb,r,s=1,21,203,3458,BBCDEFGa[0],a[1],b[0],b[1]=21,203,21,203