C++之赋值、比较、逻辑运算符

赋值运算符

**作用：**用于将表达式的值赋给变量

赋值运算符包括以下几个符号：

 int main() {

     //赋值运算符

     // =
     int a = ;
     a = ;
     cout << "a = " << a << endl;

     // +=
     a = ;
     a += ; // a = a + 2;
     cout << "a = " << a << endl;

     // -=
     a = ;
     a -= ; // a = a - 2
     cout << "a = " << a << endl;

     // *=
     a = ;
     a *= ; // a = a * 2
     cout << "a = " << a << endl;

     // /=
     a = ;
     a /= ;  // a = a / 2;
     cout << "a = " << a << endl;

     // %=
     a = ;
     a %= ;  // a = a % 2;
     cout << "a = " << a << endl;

     system("pause");

     return ;
 }

比较运算符

**作用：**用于表达式的比较，并返回一个真值或假值

比较运算符有以下符号：

 int main() {

     int a = ;
     int b = ;

     cout << (a == b) << endl; // 0 

     cout << (a != b) << endl; //

     cout << (a > b) << endl; //

     cout << (a < b) << endl; //

     cout << (a >= b) << endl; //

     cout << (a <= b) << endl; //

     system("pause");

     return ;
 }

逻辑运算符

**作用：**用于根据表达式的值返回真值或假值

逻辑运算符有以下符号：

 //逻辑运算符  --- 非
 int main() {

     int a = ;

     cout << !a << endl; //

     cout << !!a << endl; //

     system("pause");

     return ;
 }

 //逻辑运算符  --- 与
 int main() {

     int a = ;
     int b = ;

     cout << (a && b) << endl;//

     a = ;
     b = ;

     cout << (a && b) << endl;// 0 

     a = ;
     b = ;

     cout << (a && b) << endl;//

     system("pause");

     return ;
 }

 //逻辑运算符  --- 或
 int main() {

     int a = ;
     int b = ;

     cout << (a || b) << endl;//

     a = ;
     b = ;

     cout << (a || b) << endl;// 1 

     a = ;
     b = ;

     cout << (a || b) << endl;//

     system("pause");

     return ;
 }