C 中的運算子

// 算術運算子

int a = 21;
int b = 10;
int c;
c = a + b;
cout << "c = " << c << endl;
c =  a - b;
cout << "c = " << c << endl;
c = a * b;
cout << "c = " << c << endl;
c = a / b;
cout << "c = " << c << endl;
c = a % b;  // 取餘運算子
cout << "c = " << c << endl;
int d = 10;
c = d++; // 自加
cout << "c = " << c << endl;
d = 10;
c = d--; // 自減
cout << "c = " << c << endl;

// 關係運算子

int aa = 21, bb = 10;
int cc;
if (aa == bb)
cout << "aa == bb\n";
else    
cout << "aa != bb\n";
if (aa > bb)
cout << "aa > bb\n";
else    
cout << "aa < bb\n";
if (aa < bb)
cout << "aa < bb\n";
else    
cout << "aa > bb\n";
if (aa != bb)
cout << "aa != bb\n";
else
cout << "aa == bb\n"; 
aa = 5;
bb = 20;
if ( aa <= bb )
cout << "aa小於或等於bb" << endl ;
if ( bb >= aa )
cout << "bb大於或等於aa" << endl ;

a = 0011 1100

b = 0000 1101
-----------------
a&b = 0000 1100
a|b = 0011 1101
a^b = 0011 0001
~a  = 1100 0011

unsigned int a2 = 60;

unsigned int b2 = 13;
int c2 = 0;
c2 = a2 & b2;
cout << "a2 & b2: " << c2 << endl;
c2 = a2 | b2;
cout << "a2 | b2: " << c2 << endl;
c2 = a2 ^ b2;
cout << "a2 ^ b2: " << c2 << endl;
c2 = ~a2;
cout << "~a2: " << c2 << endl;
c2 = a2 << 2;
cout << "a2 << 2: " << c2 << endl;
c2 = a2 >> 2;
cout << "a2 >> 2: " << c2 << endl;

// 賦值運算子

int a3 = 21;
int c3;
c3 = a3;
cout << "c3 = " << c3 << endl;
c3 += a3;
cout << "c3 = " << c3 << endl;
c3 -= a3;
cout << "c3 = " << c3 << endl;
c3 *= a3;
cout << "c3 = " << c3 << endl;
c3 /= a3;
cout << "c3 = " << c3 << endl;
c3 = 200;
c3 %= a3;
cout << "c3 = " << c3 << endl;
c3 <<= 2;
cout << "c3 = " << c3 << endl;
c3 >>= 2;
cout << "c3 = " << c3 << endl;
c3 &= 2;
cout << "c3 = " << c3 << endl;
c3 ^= 2;
cout << "c3 = " << c3 << endl;
c |= 2;
cout << "c3 = " << c3 << endl;

語法格式：sizeof(資料型別/變數名);

cout << "size of char : " << sizeof(char) << endl;
cout << "size of int : " << sizeof(int) << endl;
cout << "size of short int : " << sizeof(short int) << endl;
cout << "size of long int : " << sizeof(long int) << endl;
cout << "size of float : " << sizeof(float) << endl;
cout << "size of double : " << sizeof(double) << endl;
cout << "size of wchar_t : " << sizeof(wchar_t) << endl;

int main ()

struct employee;

employee emp;
strcpy(emp.first_name, "zara");   點運算子
// 如果 p_emp 是乙個指標，指向型別為 employee 的物件，則要把值 "zara" 賦給物件 emp 的 first_name 成員，需要編寫如下**：
strcpy(p_emp->first_name, "zara");  箭頭運算子

7.5 c++ 指標運算子（& 和 *）

c++ 提供了兩種指標運算子，一種是取位址運算子 &，一種是間接定址運算子*。指標是乙個包含了另乙個變數位址的變數，可以把乙個包含了另乙個變數位址的變數說成是"指向"另乙個變數。變數可以是任意的資料型別，包括物件、結構或者指標。

取位址運算子 &

間接定址運算子*

int main ()

// 運算子優先順序

int a4 = 20;
int b4 = 10;
int c4 = 15;
int d4 = 5;
int e4;
e4 = (a4 + b4) * c4 / d4;      // ( 30 * 15 ) / 5
cout << "(a4 + b4) * c4 / d4 的值是 " << e4 << endl ;
e4 = ((a4 + b4) * c4) / d4;    // (30 * 15 ) / 5
cout << "((a4 + b4) * c4) / d4 的值是 " << e4 << endl ;
e4 = (a4 + b4) * (c4 / d4);   // (30) * (15/5)
cout << "(a4 + b4) * (c4 / d4) 的值是 " << e4 << endl ;
e4= a4 + (b4 * c4) / d4;     //  20 + (150/5)
cout << "a4 + (b4 * c4) / d4 的值是 " << e4 << endl ;

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